2/16 Prof. Junichiro Kono (Rice University)
Cavity QED in the Ultrastrong Coupling Regime
Strong resonant light-matter coupling in a cavity setting is an essential ingredient in fundamental cavity quantum electrodynamics (QED) studies as well as in cavity-QED-based quantum information processing. In particular, a variety of solid-state cavity QED systems have recently been examined, not only for the purpose of developing scalable quantum technologies, but also for exploring novel many-body effects inherent to condensed matter. This talk will first describe our recent observation of collective ultrastrong light-matter coupling in a 2D electron gas in a high-quality-factor terahertz cavity in a quantizing magnetic field, demonstrating a record-high cooperativity . The electron cyclotron resonance peak exhibited splitting into the lower and upper polariton branches with a magnitude that is proportional to the square-root of the electron density, a hallmark of collective vacuum Rabi splitting. The second part of this talk will present 1D microcavity-exciton-polaritons in a thin film of aligned carbon nanotubes  embedded in a Fabry-Perot cavity, also exhibiting collective ultrastrong light-matter coupling. These experiments open up a variety of new possibilities to combine the traditional disciplines of many-body condensed matter physics and cavity-based quantum optics.
1/10 Prof. Yoshifumi Tanimoto (Hiroshima University)
10/2 Dr. William Knafo (Centre National de la Recherche Scientifique)
High-field magnetism in the heavy-fermion materials CeRh2Si2 and URu2Si2
Extreme conditions of intense magnetic field and high pressure are powerful tools to tune the microscopic interactions and explore the magnetic phase diagrams of strongly-correlated electrons systems, as heavy-fermion magnets. An introduction to the LNCMI-Toulouse pulsed field facility will be given, with a focus on recent technical advances, as the generation of non-destructive pulsed fields up to 99 T, the combination of pulsed fields up to 60 T and high pressures up to 4 GPa, and the possibility to perform neutron diffraction under long-duration pulsed fields up to 40 T. Then I will show recent experimental studies performed using these new setups.
8/3 Mr. Fumiya Katsutani (Rice University)
ルトップ型のミニコイルパルスマグネットを開発した。光学窓一つを通して試料に直接アクセスでき、パルス強磁場下での超高速分光、非線形光学分光、顕微分光に最適である。このシステムを使って行った最近の実験から、近赤外分光およびテラヘルツ分光の幾つかの例を紹介する。半導体量子井戸での時間分解発光実験では、インコヒーレントに励起された電子・正孔系か巨視的コヒーレンスが自発的に発生するDicke superradianceの特殊例であるsuperfluorescenceを観測した。これにより、有限の遅延時間の後にコヒーレント放射のバーストが生じる。アメリカ国立強磁場研究所における以前の我々の測定と比較して、光パルスの光ファイバーによる分散がないことにより時間分解能を改善し、superfluorescenceの遅延時間とパルス幅の最大値を決定することに成功した。真性シリコン中の光励起キャリアのサイクロトロン共鳴を、30 Tパルスマグネットとシングルショットテラヘルツ時間領域分光器を組み合わせることによって測定した。階段状光学素子の導入によって空間的にプローブ光に遅延を与え、単一のパルス光からテラヘルツ帯での時間分解実験が可能となる。光励起キャリアのサイクロトロン共鳴吸収の磁場依存性から、キャリア有効質量m*はm0を真空中の自由電子質量として0.19m0と求まる。我々はまた、近赤外領域のバンド端でのセレン化インジウム（InSe）の円偏光依存磁気吸収分光を行った。 0 Tで約1.32 eVに観測される1s励起子ピークの磁場による反磁性シフトとゼーマン分裂を30 Tまで測定し、反磁性シフト定数σ= 4.08×10 -3 meV/T-2および有効g因子geff = 2.12を決定した。
6/4 Dr. Jan J. Dubowsk (Université de Sherbrooke)
Biosensing Applications of Digital Photocorrosion in GaAs/AlGaAs Nano-Heterostructures
Etching of semiconducting materials at rates approaching atomic level resolution is of high interest to the advancement of technologies addressing fabrication of low-dimensional devices, tunability of their optoelectronic properties and precise control of device surface structure. The so-called digital etching that takes advantage of a self-limiting reaction has the potential to address some of these challenges. However, conventional applications of this approach proposed almost 30 years ago, require specialized and expensive equipment, which contributed to a relatively slow progress in penetration of digital etching to micro/nanofabrication processing schemes. We have observed that for photoluminescence (PL) emitting materials with negligible dark corrosion, it is possible to carry out PLmonitored photocorrosion in cycles analogous to those employed in digital etching. The advantage of this approach is that photocorrosion of materials, such as GaAs/AlGaAs heterostructures, could be carried in a water environment. This digital photocorrosion (DIP) process could be carried out in cycles, each approaching sub-monolayer precision. I will discuss fundamentals of DIP and, in particular, mechanisms responsible for achieving high-resolution etch rates of semiconducting materials. For instance, we have demonstrated a successful dissolution of a 1-nm thick layer of GaAs embedded between Al0.35Ga0.65As barriers in a 28% NH4OH:H2O, and we claimed that under optimized conditions a further enhanced resolution is feasible. The nm-scale depth resolution achieved with DIP and lowcost of the instrumentation required by this process is of a potential interest to specialized diagnostics, structural analysis of multilayer nanostructures and, e.g., revealing in situ selected interfaces required for the fabrication of advanced nano-architectures. We have explored the sensitivity of DIP to perturbations induced by electrically charged molecules, such as bacteria, immobilized on semiconductor surfaces. Here, I will highlight our recent studies on detection of Escherichia coli and Legionella pneumophila bacteria immobilized on antibody functionalized GaAs/AlGaAs biochips. I will also discuss the application of this approach for studying antibiotic reactions of bacteria growing on biofunctionalized surfaces of GaAs/AlGaAs biochips.
11/1 Dr. Akihiko Ikeda(Research Associate)
Quantum spin-crossover of correlated electrons
Spin state is a characteristic degree of freedom in a multi-electron and multi-orbital system (e.g. magnetic ion under crystal field) where crystal field splitting (Δ) and Hund's coupling (J ) are delicately competitive. Low spin [LS] (or high spin [HS]) state emerges when Δ (or J ) overwhelms the other. Recently, we found a low entropy phase in a spin crossover cobaltite LaCoO3 at ultrahigh magnetic fields of above 100 T by means of magnetization measurement up to 140 T . Various exotic orders are claimed as its origin such as LS/HS order and excitonic order. They are considered to be stabilized by the correlation effects based on analysis of the two-orbital Hubbard model [2, 3]. The excitonic phase is characterized with the spontaneous and quantum-mechanical mixing of the wave functions of LS and HS states. Whereas, the LS/HS ordered phase is the spatial alternation of the LS and HS states.
9/25 Prof. Kenichi Asano (Osaka University)
放物線形のエネルギー分散を持つ電子系に対するサイクロトロン共鳴には相互作用効果が現れない。この事実は Kohn の定理として知られている。
しかし、グラフェンに代表される Dirac 電子系（線形のエネルギー分散を持つ二次元電子系）には、この Kohn の定理を適用できないので、サイ
フェン系については、N=0 のランダウ準位から N=1 のランダウ準位への遷移に対応するサイクロトロン共鳴にほとんど多体効果が現れず、Kohn の
定理が近似的に成立しているとみなせることが分かった。その一方で、N=-1 からN=2 への遷移に対応するサイクロトロン共鳴には相互作用効果が
4/8 Dr. Atsuhiko Miyata (Laboratoire National des Champs Magnetiques Intenses, Toulouse, France)
Direct measurements of the exciton binding energy and effective masses for charge carriers in organic-inorganic perovskites
Solar cells based on the organic-inorganic perovskite family of materials
have made a dramatic impact on emerging photovoltatic (PV) research with
efficiencies of around 20% , which offers a new route to low-cost solar
energy devices with simple fabrication processes. However, the fundamental
electronic properties of the perovskites such as the electron and hole
effective masses and the exciton binding energy are poorly known. We have
measured both properties for methyl ammonium lead tri-iodide (CH3NH3PbI3)
using magneto absorption in very high magnetic fields up to 150 T showing
that the exciton binding energy at low temperatures is only 16 meV, a value
three times smaller than previously assumed . Landau level spectroscopy
shows that the reduced effective mass of 0.104 me is also smaller than
previously assumed , but in good agreement with recent calculations
. We also observe Landau levels in the room temperature phase (350 K
> T > 140 K) in which PV devices actually perform, showing an evidence
that the binding energy falls to a few milli-electron volts in the room
temperature. This result indicates the performance of PV devices using
this material is attributed to the spontaneous generation of free carriers
4/3 Dr. Sergei Zherlitsyn (HLD-EMFL, Germany)
Spin-lattice effects in high magnetic fields
The Dresden High Magnetic Field Laboratory (HLD) is a pulsed-field user facility which currently operates ten experimental chambers equipped with a variety of pulsed magnets energized by two capacitor banks with maximum stored energies of 50 and 14 MJ at 24 kV maximum operational voltage. The magnets support a broad range of experiments in pulsed magnetic fields for user and in-house research. In the first part of my talk I will present some recent developments at the HLD.
Spin-lattice effects play an important role in many magnetic materials, frequently leading to novel phases and phase transformations. In this presentation, I give some examples of such effects studied in frustrated magnets characterized by competing interactions. The delicate balance between these interactions can be easily disturbed by the application of strong magnetic fields leading to field-induced phase transitions. The phase transformations and the related critical phenomena in magnetic systems are fruitful grounds for ultrasound experiments which provide valuable information on the spin-strain coupling. I discuss the sound-velocity and sound-attenuation results obtained in magnetic fields up to 87 T for some selected materials with a magnetic pyrochlore lattice, such as CdCr2O4 and CoCr2O4 which exhibit unusual phase transitions and extended metastable magnetostructural states. I will show that the spin-strain coupling is crucial and determines the underlying physics of the frustrated magnetic materials.
1/28 Prof. Hirohiko Sato (Chuo University)
1/23 Ms. Suyeon Lee (IMGSL）
Magnetic field-induced insulator-metal transition in transition metal oxides at ultrahigh magnetic fields
1/19 Prof. Kim Yongmin (Department of Applied Physics Dankook University, Yongin si, Korea)
Negative Diamagnetic Shift in InP-GaP Lateral Nanowires under Pulsed Magnetic Fields and a Progress Report on Developing Pulsed Magnetic Field Facility at Dankook University
While growing a short period superlattice (SPS), due to an in-plane strain field along  direction, depositing atoms cross penetrate, which spontaneously generates potential modulation along the lateral  direction. In such growth condition, lateral superlattice can be achieved. Limiting the thickness of the SPS layer, similarly, one can grow a lateral nanowire. We measured photoluminescence (PL) of an InP-GaP lateral nanowire under pulsed magnetic fields to 50 T. We observed strong negative diamagnetic shift in a certain magnetic field direction due may to a variation of exciton center of mass potential. We will also discuss the current achievement of pulsed magnetic field facility at Dankook University. We successfully developed 1.6 MJ (9 kV) capacitor bank for the generation of pulsed magnetic fields. We obtained ~47 T at 6 KV charging voltage with the 22 ms total transient time of the magnetic pulse. We plan to develop higher and longer magnetic field facility in future.
1/14 Prof. Hsiang-Lin Liu (Department of Physics, National Taiwan Normal University)
THz response of graphene-based materials
We present the results of THz absorption measurements of monolayer graphene with molecular doping and four-layer graphene. There are several important findings in this study. First, the THz conductivity of the triazine-doped film consists of free carrier absorption at zero frequency and a disorder-induced finite frequency peak around 4.65 THz. As the temperature is lowered, the Drude plasma frequency (30 THz) decreases, whereas the carrier relaxation time (54 fs) does not show much temperature variation. These scenarios show the semiconducting behavior of the triazine-doped film. Second, a comparison of our measured conductance spectra and the theoretical predictions in turn illuminates the importance of the several scattering mechanisms present in these materials. Third, in a magnetic field, the Drude oscillator strength of four-layer graphene is suppressed and transferred to various finite frequency transitions between the Landau levels. The dramatic increase of the low-frequency transmission is a THz counterpart of the positive magnetoresistance effect. The 300 K magnetodielectric contrast is as large as 60% near 1 THz at 10 Tesla. The results are potentially useful for magnetic memory applications away from the dc limit.
12/11 Dr. Gael Bastien (CEA-Grenoble)
Fermi surface and upper critical field study of UCoGe under hydrostatic pressure
UCoGe is a ferromagnetic superconductor with a Curie temperature of T_C ~ 2.8 K and a superconducting transition at T_sc ~ 0.6 K. The Curie temperature decreseases with pressure and vanishes at a critical pressure p_c~ 1 GPa .
Superconductivity was observed both below and above p_c. At ambient pressure in the ferromagnetic phase the upper critical field as a function of temperature shows an unusual upward curvature .
We report magnetoresistance and Hall effect measurements on UCoGe for field along the easy magnetization axis c.
We focused mainly on Shubnikov-de Haas oscillations and on the temperature dependence of the upper critical field as function of pressure in the ferromagnetic and paramagnetic states.
At ambient pressure an anomaly around 9T and a Fermi surface reconstruction around 17 T were observed both in the quantum oscillations and in the Hall effect.
Quantum oscillations evolve continuously with pressure between ambient pressure and 2.3 GPa, no Fermi surface reconstruction was observed around the critical pressure p_c.
Finally it was shown that the upper critical field of UCoGe for field along the easy magnetization axis c increases with pressure through the critical pressure p_c and the upward curvature of the upper critical field is also enhanced above the critical pressure.
10/17 Mr. Ayumu Iwasa (IMGSL)
Experimetal search for a new high-field phase of the semimetals Bi and BiSb
7/25 Mr. Kazuto Akiba (IMGSL)
Research of semimetals under pulsed high magnetic fields
5/30 Dr. Zhou Weihang (IMGSL)
High-field Magneto-optical Study on the Excitonic and Phononic Transitions in Single-walled Carbon Nanotubes
4/30 Dr. Atsushi Miyake (IMGSL)
Current status of solid state physics reseach in Tokunaga laboratory
3/30 Dr. Akihiko Ikeda (IMGSL)
Current status of solid state physics reseach in Matsuda laboratory
2/21 Dr. Akihiro Kondo (IMGSL)
Current status of solid state physics reseach in Kindo laboratory
1/30 Dr. Daisuke Nakamura (IMGSL)
Current status of solid state physics reseach in Takeyama laboratory
8/16 Prof. Alexander T. Holmes (School of Physics and Astronomy, University of Birmingham, UK)
Neutrons and X-rays at high field, from superconductors to viruses
9/4 Dr. S. Zherlitsyn(Hochfeld-Magnetlabor Dresden, Helmholtz-Zentrum Dresden-Rossendorf, Germany)
High Magnetic Fields for Science
Magnetic fields are powerful tools for studying the state of matter. Under extreme conditions, such as high-magnetic fields, new interesting properties of matter can appear and an understanding of materials behavior can be gained. Access to high magnetic fields could provide new insight into various fundamental physical phenomena. Currently the only ways to reach magnetic fields beyond 50 T are pulsed magnets. The Dresden High Magnetic Field Laboratory (Hochfeld-Magnetlabor Dresden, HLD) has achieved the strongest non-destructive magnetic fields in Europe. Last year the HLD held the world record for some time. Typical pulse durations of the available magnets are from 0.01 to 1 s that is long enough for many experiments which are usually performed in static magnetic fields. Magnetic fields up to about 90 T are available for user experiments such as electrical transport, magnetization, ultrasound, magnetostriction, electron spin resonance, and high-field infrared spectroscopy. Several less typical pulsed-field experiments, for instance, nuclear magnetic resonance or specific heat are also emerging at the HLD now. In my talk I explain how the pulsed fields are generated and applied for various scientific experiments. I will show you recent results obtained on some magnetic systems in high magnetic fields. Results of high-field ultrasound investigations will be analyzed in more details. I acknowledge support from the "JSPS Invitation Fellowship Program for Research in Japan (Short-term)".
8/7 Mr. Mitsuru Inagaki (Toyota Technological Institute)
5/30 Mr. Raju Kati (Department of Physics, Osmania University, India)
Elastic and anelastic behaviour of some charge ordered manganites
The Physics of these manganite materials is dominated by complex interplay between charge, spin and lattice degrees of freedom. The correlation between charge and spin has been well studied and explained. But, there is limited knowledge on how the lattice interact with the charge and spin in these materials, because the lattice related properties are to be studied with care by making use of non destructive techniques. Therefore, systematic studies of elastic longitudinal modulus and internal friction behaviour along with magnetic and electrical properties of the samples have been studied. In doped manganites, the charge-ordered phases are novel manifestations arising from the interaction between the charge carriers and phonons where in the Jahn-Teller distortions play a significant role. Charge ordering (CO) arises because the carriers are localized into specific sites below a certain temperature known as charge ordering temperature, TCO, giving rise to long- range order throughout the crystal structure. Although, charge ordering would be expected to be favored when doping level x = 0. 5, due to the presence of equal concentrations of Mn3+ and Mn4+ states, the phenomenon is found be present in the doping range, 0.3 < x < 0.75. The physical properties in CO manganites arise from the strong competition between ferromagnetic double-exchange and antiferromagnetic superexchange interactions. Under high magnetic fields, the charge ordered state melts leading to the formation of CMR state. At Charge Ordered transition temperature, a jump in resistivity, a peak in magnetization and structural phase transitions etc., may be observed. Although a few studies on these charge ordered materials were reported earlier, several other aspects of these materials including electron phonon and spin phonon interactions have not been understood clearly. Therefore, the present investigation is aimed at understanding the electron phonon and spin phonon interactions in these materials. The motivation for undertaking the electrical and magnetic property investigation along with the elastic and anelastic studies has also been explained. One of the most important characteristic properties of CMR materials is the exhibition of metal-insulator transition (TP). The electronic properties of these materials are known to change with doping at A-site. Depending on the concentration of Mn3+/ Mn4+ ions and mean ionic A-site ionic radius, these materials also show charge-ordering transitions (TCO). Therefore, in order to determine their TP and TCO values and to investigate their variation with doping material concentration, resistivity measurements were undertaken over a temperature range, 2 - 300K using four - probe method on a superconducting magnetic system (Oxford Spectromag). The variation of TP and TCO with dopant concentration has been discussed. The resistivity data of all the samples has been thoroughly studied in the presence of magnetic fields and the results demonstrate a clear decrease of resistivity in the magnetic field. The resistivity below TCO drastically reduced, exhibiting a large CMR effect. The large decrease of the resistivity and the downward shift of TCO upon the application of a field manifest the unstable nature of the CO state. Thus melting of CO state in a magnetic field and the unusual resistivity behavior in magnetic field may be explained within the framework of the phase separation. The fundamental property of mixed-valence manganites is the close relationship between electronic transport and magnetism. A key feature of these materials is the simultaneous occurrence of metal-insulator (TP) and ferro-paramagnetic transitions (TC). Depending on the composition of samples, they exhibit different magnetic transitions viz., Curie transition (TC), Charge ordering transition (TCO) and Neel transitions (TN). The magnetic transition temperatures were obtained by measuring magnetization values as a function of temperature using Vibrating Sample Magnetometer (VSM) over a temperature range, 80-300K and their variation with compositions is explained in detail. The materials characterization is a serious challenge in many fields of technology. The ability of the technique to explore the structural and mechanical properties of materials is essentially required for many applications of the materials. Therefore, the determination of elastic and anelastic behaviour is vital for the discovery of newer materials. The measurement of ultrasonic velocities (longitudinal) and attenuation in materials directly relates the elastic properties of materials. The structural changes in the materials are well reflected in density/velocity and hence, the modulus. The phenomenon such as fatigue, creep and materials strength can be explained through change in ultrasonic velocities. Thus, the measurement of ultrasonic velocity, attenuation and elastic constants is an important ultrasonic non-destructive testing (NDT) for quality assessment of materials. The data on newer materials such as CMR materials, composites, and ceramics as a function of temperature and frequency are required for the selection of right material for a particular application. Therefore, to measure the elastic properties of these charge ordered manganites in the temperature range 100 300 K, composite oscillator technique has been used. The low temperature elastic and anelastic behaviours of magnetic materials in general and CMR materials in particular are very much useful in understanding the electron phonon and spin phonon couplings. All the samples of present investigation are found to exhibit a minimum in the longitudinal velocity in the vicinity of their respective TC's and TCO's. In recent times, although several theoretical models were proposed, mean field theory incorporating the ideas relating to the Jahn-Teller effect seems to be better one in explaining the anomalous behaviour of magnetic oxides in general and manganites in particular in the vicinity of their transition temperatures. Therefore, an attempt has been made to explain the anomalous elastic behaviour in the vicinity of magnetic transitions observed in the present investigation using the mean field theory. The important criterion based on which the mean field theory was developed, is the existence of an interaction between a lattice distortion (i. e elastic strain) and wave function of degenerate ground state, which lifts the degeneracy causing the molecule to seek a distorted configuration of lower energy.
5/21 Prof. Giti A. Khodaparast (KEK)
Magneto-Optical Spectroscopy of MOVPE Grown Narrow Gap III-Mn-V Ferromagnetic Semiconductors
Narrow gap ferromagnetic semiconductors (NGFS) have significant potential for applications in both infrared spin photonics and spin transport devices due to their lighter holes, smaller energy gaps, and much higher carrier mobilities compared to other III-Mn-V ferromagnetic semiconductors. A Rudermann- Kittel-Kasuya-Yosida (RKKY) mechanism, where free holes mediate the ferromagnetism, is favored in NGFS and a small hole effective mass results in a long interaction distance and effective exchange coupling. The calculated hole effective Bohr radius in NGFS indicates sufficient overlap of the hole wave functions to stabilize ferromagnetism for hole concentrations greater than 1018 cm-3. In this work, several time resolved differential transmission and magneto-optical spectroscopy techniques were employed to provide insight into both the time scales and the nature of microscopic interactions in MOVPE grown ferromagnetic InMnAs and InMnSb with the Curie temperatures above room temperature.
4/16 Prof. Eiji Nakamura (KEK)
Proposal of applications of the MegaGauss techniques for higher-energy charged particle handling
The MagaGauss techniques are attractive to explore a frontier of physics study for high-energy particles. The following three articles are discussed for examples of the applications: (1) Beam handling of GeV ~ PeV hadrons at high-energy particle accelerators, (2) Compact fusion reactor, (3) Improvement of light source for short wavelength of 1 fm, which is equivalent to the core size of nucleon, produced by the synchrotron radiation method. It is difficult to apply the MegaGauss technique because severe stability and homogeneity are required for such high- energy charged particle handling now. I would like to solve the problems, and realize a new energy field.
2/13 Dr. Zhou Weihang (IMGSL)
The Quantum Chaotic Dynamics of Hydrogen-like Shallow Impurities in Solid State Environment
In this work, we report the first experimental study on the quantum chaotic dynamics of hydrogen analogues in solid state environment. We realized the hydrogen analogue in anisotropic crystal field by introducing an isolated phosphorus donor in Si and study its quantum chaotic dynamics by means of photo- thermal ionization spectroscopy technique. The interference of electron wave packets which leads to quasi-Landau resonances were observed. By analyzing the magnetic field dependence of the statistical energy level distributions, we observed smooth transitions between the Poisson limit and the Wigner limit for the impurity energy level distributions, demonstrating the magnetic field control of the quantum chaotic dynamics of hydrogen analogues in an anisotropic crystal field. Effects of the crystal field anisotropy on the quantum chaotic dynamics have been studied and good agreements between theoretical calculations and the experimental data were found.
2/3 Prof. Tung-Ming Pan(Chang Gung University)
High-k Rare-Earth Oxide for Thin-Film Transistors, Nonvolatile Memories, pH Sensors, and Biosensors Applications
We have developed high-k rare-earth oxide films for TFTs, nonvolatile memories, pH sensors, and biosensors applications. High-k Pr2O3 and Tb2O3 dielectrics deposited on poly-Si film using a N2O and CF4 plasma treatment exhibited excellent electrical characteristics, respectively. Consequently, the concentration of nitrogen and fluorine in the oxide/poly-Si interface has to be optimized in terms of the reliability reduction due to hot carrier and positive-bias temperature instability. The stacked Pr2O3/SiOxNy film and Tb2O3 are very attractive as gate dielectric materials for high performance low-temperature poly-Si TFTs. High-k Y2O3 memory device annealed 700oC in N2 ambient exhibited excellent electrical characteristics, such as memory window, gate disturb, data retention, and endurance. This is due to the formation of Y-silicate layer after annealing in N2 ambient. Furthermore, our group explored Nd2O3, Er2O3, and Sm2TiO5 films to replace a traditional SiO2 film as the sensing membrane in pH-ISFET devices. These metal oxides deposited on Si by reactive sputtering exhibit a high detection sensitivity, small hysteresis voltage, and low drift rate. EIS devices incorporating high-k rare-earth sensing membranes appear to be very promising SOC systems for use in biomedical engineering application.
1/30 Dr. Moaz Altarawneh (Department of Physics, Mu'tah University)
Radio Frequency Contactless Methods in Pulsed Magnetic Field
Radio frequency (rf) contactless methods are useful to study a wide range of physical properties in materials. In metals, skin depth and sheet resistance are accessible, in superconductors upper critical fields and penetration depths can be determined, and in magnetic materials dynamical susceptibility and magnetic transitions can be measured. Advantages of rf measurements include the high sensitivity, high stability oscillator circuits and the contactless nature of the measurement. The tunnel diode oscillator is one of the common rf methods that is proved to be very powerful method in different experimental environments.
1/23 Prof. John Singleton (National High Magnetic Field Laboratory, Los Alamos National Laboratory)
Magnetic quantum oscillations in underdoped cuprate superconductors observed using the Los Alamos 100 T Multi-Shot Magnet
Magnetic quantum oscillations in single crystals of several underdoped cuprates YBa2Cu3O6+x have been observed using the Los Alamos 100 T Multi-Shot Magnet. Typical data for x = 0. 61, measured using a MHz contactless conductivity technique, are shown in the figure; the frequency shift is proportional to the change in conductivity. The quantum oscillation frequencies and effective masses obtained suggest that the Fermi energy in the cuprates has a maximum at a hole doping of p ~ 0.11-0.12. On either side, the effective mass may diverge, possibly due to quantum-critical phase transitions associated with the T = 0 limit of the metal-insulator crossover (low-p side), and the topological transition from small to large Fermi surface close to optimal doping (high p side). These results will be compared with other data for the cuprates and recent models in order to build up a picture of the probable Fermi surface and its dependence on doping.
11/18 Dr. Xuan Luo (Pohang University of Science and Technology)
Orbital physics and magnetocaloric effect in spinel vanadates
The orbital physics of spinel vanadates (ZnV2O4 and MnV2O4) are most investigated prototypical systems to study the different couplings between spin, orbital and lattice degrees of freedom. I will talk about the phase diagram of the Zn-doped MnV2O4 system. The ferromagnetic orbital order appears in the parent compound MnV2O4 and low Zn-doped compounds. Additionally, I will talk about the large magnetocaloric effect is observed in this spinel vanadate. It might be due to the change of the orbital state of V3+ induced by an applied magnetic field around the phase transition temperature.
11/18 Dr. Bosen Wang (Institute of Solid State Physics, Chinese Academy of Sciences)
Chemical composition-dependent magnetocaloric effect and giant magnetoresistance in antiperovskite GaCMn3
In this presentitation, manganese-based antiperovskite compound GaCMn3 is selected to study the physical properties of the parent compound and the physical mechanisms of the magnetic transitions systematically. Our results indicate that GaCMn3 are electron-correlated itinerant ferromagnetisms commonly due to strong hybridizations of C2p-Mn3d and that the physical mechanisms could be attribute to the reconsitution of Fermi surface around the first-order magnetic transition. Based on systemic chemical substitutions, we optimize the functional parameters (GMR and MCE) and analysis the chemical doping phase diagram. For GaCMn3, partial substitutions of Ni for Mn or Zn for Ga enhance the antiferromagnetic metastability, resulting in the occurrences of GMR( 80%, at 50kOe) and adjustable MCE.
4/25 Dr. Daisuke Nakamura (IMGSL)
Terahertz electrical conductivity measurement of the cuprate superconductor thin films
2/15 Dr. William Knafo (LNCMI, Toulouse France)
Study of heavy-fermion systems in pulsed magnetic field
In this talk, I will present recent studies of heavy-fermion systems performed at the LNCMI-Toulouse (France) in pulsed magnetic fields up to 60 T. Heavy fermions are characterized by relatively small energy scales which can be easily tuned by pressure or doping, leading generally to a quantum instability between a paramagnetic and an antiferromagnetic ground states. The application of a magnetic field is an alternative to induce a quantum phase transition on these systems, which are driven in high fields to a polarized paramagnetic state.
An investigation of the magnetic field - temperature phase diagram of CeRh2Si2 by resistivity, torque, magnetostriction, and thermal expansion measurements will be presented. CeRh2Si2 is an antiferromagnet which becomes superconducting in the neighbouring of its pressure-induced quantum phase transition to a paramagnetic regime, at around 11 kbar. High fields applied along the easy-axis c permit to tune the system to a polarized paramagnetic regime above 26 T . The magnetic field- temperature phase diagram is found to be composed of (at least) three different antiferromagnetic phases. The magnetic-field and pressure-dependences of the quadratic exponent A of the resistivity indicate a similar enhancement of the effective mass at the pressure- and field-tuned quantum instabilities in CeRh2Si2 , which suggests that both kinds of criticality are controlled by common features.
9/28 Prof. Yan Chen (Fudan University)
Exploring FFLO states of polarized fermions in cold atoms and condensed matter systems
The BCS theory explains conventional superconductivity in terms of electrons
with opposite spin and momentum that condense into pairs. A sufficiently
large magnetic field destroys superconductivity by coupling to the orbital
motion of the electrons. In 1964, Fulde & Ferrell and Larkin &
Ovchinnikov (FFLO) showed that this coupling would give rise to a state
different to the conventional BCS-state. In particular, this state may
exhibit a spatially modulated order parameters as well as finite momentum
of Cooper pairs. Up to now, the FFLO state is still elusive to experimental
observation. In the talk, I will discuss our theoretical studies on the
FFLO states of polarized fermions in cold atoms and condensed matter systems.
First we investigate the superfluidity with imbalanced populations of harmonically
trapped ultracold fermions in a 2D optical lattice. In the high- density
regime, a novel FFLO state with gap oscillation along the angular direction
shows up and the accompanying ferromagnetic order modulates accordingly.
Next we study the electronic properties of a heterostructure consisting
of ferromagnetic metallic layer and s-wave superconductor layer. We demonstrate
that a novel stripe FFLO state as well as a 2D FFLO state may show up due
to the proximity effect.
9/17 Prof. Jochen Wosnitza (Hochfeld-Magnetlabor Dresden (HLD))
Research at the Dresden High Magnetic Field Laboratory
High magnetic fields are one of the most powerful tools available to scientists for the study, modification, and control of the state of matter. The application of magnetic fields, therefore, has become a commonly used instrument in condensed-matter physics. For the observation of many phenomena very high magnetic fields are essential. Consequently, the demand for the highest possible magnetic-field strengths is increasing. At the Dresden High Magnetic Field Laboratory (Hochfeld-Magnetlabor Dresden, HLD), that in 2007 has opened its doors for external users, pulsed magnetic fields up to 70 T are available and a European record field of 87.2 T has been reached. The laboratory has set the ambitious goal of reaching 100 T on a 10 ms timescale. As a unique feature, a free-electron-laser facility next door allows high-brilliance radiation to be fed into the pulsed field cells of the HLD, thus making possible high-field magneto-optical experiments in the range 3-250 um. Cryotechniques and different sample probes for a broad range of experimental techniques custom designed for the pulsed magnets are readily available for users. In-house research of the HLD focuses on electronic properties of strongly correlated materials at high magnetic fields. Besides introducing some highlights of the HLD experimental infrastructure, some recent scientific research results will be presented.
3/30 Prof. Oliver Portugall(Laboratoire National des Champs Magnetiques Intenses CNRS)
The LNCMI - technical installations, recent scientific highlights and future plans
In the first part of the talk I will present the installations and technical activities of the French national high magnetic field laboratory (LNCMI). The LNCMI features two sites at Grenoble and Toulouse respectively dedicated to the generation and application of static and pulsed magnetic fields. Both sites are subject of specific upgrade plans that will be explained.
2/4 Prof. YUDSON, Vladimir(Russian Academy of Sciences, Russia / ISSP)
Conductivity of Layered Systems: Localization vs Delocalization by Disorder
Conductivity of many layered materials is more anisotropic than it is predicted by theband theory and Drude model. To understand this anomaly, we consider a model wherethere are two kinds of the disordrr a "planar" disorder due to the presence of randomly spaced "wrong" planes, and a weak "bulk" disorder caused by isotropic impurities located randomly in the bulk of the material. This model has been solved numerically and analytically, with the use of an exact solution for the conductivity of a strictly onedimensional (1D) disordered system. Bulk disorder destroys 1D localization along the c-axis (perpendicular to the layers) which would be in the absence of the bulk disorder. Hence, the conductivity along the c-axis is finite and is proportional to the weak scattering rate by bulk impurities The out-of-plane conductivity turns out to be of a non-Drude form, and this may result in a much stronger anisotropy of the conductivity than it follows from the band theory for systems with only a bulk disorder.
1/26 Prof. Yuping Sun(Chinese Academy of Sciences Hefei, China)
Introduction to Steady High Magnetic Field Facilities in China
10/6 Prof. Hark Hoe Tan(The Australian National University)
Semiconductor Quantum Dots and Nanowires for Optoelectronic Applications
Quantum confined structures are utilised in a variety of applications due to the quantum confinement effect that leads to device improvement. The mature epitaxy technology has allowed us to grow quantum dot (QD) structures with unique electronic and optical properties. These QDs have found applications in optoelectronic devices such as lasers and photodetectors and show superior performance in comparison their quantum well counterparts. In this part of the talk, I will present the results of metal-organic chemical vapour deposition-grown QDs and discuss how the various growth parameters affect the properties of the QDs. The results of QD lasers and infrared photodetectors will be briefly presented. Selective area epitaxy is used as a way of controlling the nucleation of QDs to achieve device integration. By patterning the wafers, local growth rates can be varied depending on the dimensions of the masks and hence the density, size and composition of the QDs could be finely tuned. By using this technique, I will present the results of our integrated QD devices.
8/17 Prof. Yongmin Kim (Dancock University, Korea)
Magnetic field induced softening of the tunneling gap in modulation-doped GaAs/AlGaAs asymmetric coupled double quantum wells
We present optical transitions performed on a series of GaAs/AlGaAs asymmetric coupled double quantum well structures (ACDQW, Fig. (a)) in magnetic field (~45 T). The conduction band in such ACDQW structures has symmetric (E1) and antisymmetric (E2) subbands located energetically in close proximity through a tunneling gap ( Δsas). The valence band on the other hand has only one heavy hole level because the valence band quantum well on the substrate side is unbound.
7/17 Prof. Shojiro Takeyama (IMGSL)
7/17 Prof. Masashi Tokunaga (IMGSL)
7/3 Prof. Jan J. Dubowski(University of Sherbooke, Canada)
Quantum Dot Template Biosensor
The conventional schemes for detection of viruses, bacteria, fungi and toxins include cell culture, immunological methods and molecular methods such as polymerase chain reaction . These techniques, however, require much time and expertise in both sample preparation and data analysis. Development of alternative methods of detection that would be easy (automated), fast and specific for targeted biomolecules would be advantageous for medical diagnostics, clinical analysis or field tests.
6/26 Prof. Yasuhiro H. Matsuda (IMGSL)
6/19 Dr. Eiji Kojima (IMGSL)
5/29 Prof. Koichi Kindo (IMGSL)
5/8 Prof. Fritz Herlach(Katholieke Universiteit Leuven)
Milestones and highlights in the design and use of pulsed magnets
The development and use of pulsed magnets reviewed, beginning with the groundbreaking work of P. Kapitsa around 1925 up to the development of big dedicated pulsed field laboratories. For fields exceeding 100 T, the range goes from flux compression driven by high explosives and by electromagnetic forces to the exploding single turn coil that has been the workhorse for experiments for more than a decade.
3/25 Dr. Yoshimitu Kohama (NHMFL)
3/18 Mr. Ryo Sakakura (IMGSL)
2/24 Mr. Hiroya Suzuki (IMGSL)
2/17 Mr. Kenichi Takeda (IMGSL)
1/27 Ms. Ineko Katakura (IMGSL)
1/13 Dr. Her Jim-Long (IMGSL)
Observation of Magneto-Dielectric Coupling on Spinel Compound, CdCr2S4
We observe new interesting behavior and phase transition in this cubic spinel system from dielectric and magnetic measurements. Two types of dipolar ordering states are clearly identified. First, a glassy type dipolar ordering near the fluctuating region of the Curie temperature TC ~ 85 K was observed, which was stimulated by the onset of ferromagnetic ordering. Second, a new ferroelectric ordering was arisen at near Tp~ 56 K by applied external electric field. The magnitude and step-up temperature of dielectric constant () near TC are suppressed by electric field while increased by magnetic field. However, both electric and magnetic fields colossally enhance the magnitude of dielectric constant () near Tp. Attempt has been made to analyze these field dependent properties by considering strong spin-lattice coupling and exchangestriction effect in this crystal.
12/16 Mr. Atsuhiko Miyata (IMGSL)
12/9 Mr. Tadahiro Hosoya (IMGSL)
12/2 Mr. Masahiro Iwaki (IMGSL)
11/28 Prof. Tatsuo Kobayashi (Okayama University)
11/25 Prof. Liang Li (Wuhan University, China)
The Progress at Wuhan Pulsed High Magnetic Field Center
Wuhan Pulsed High Magnetic Field Facility is under development. Magnets of bore sizes from 12 to 34 mm with the peak field in the range of 50 to 80 T have been designed. The pulsed power supplies are a 12 MJ, 25 kV capacitor bank and a 100 MVA/100 MJ flywheel pulse generator. A prototype 1 MJ, 25 kV capacitor bank are under construction. Five magnets wound with CuNb wire, copper wire and the combination of them have been developed to be tested to verify the design. The design and analysis of the pulsed magnets and the power supply are presented.
11/17 Mr. Yuki Otsubo (IMGSL)
11/11 Mr. Yasuhiro Hirayama (IMGSL)
10/21 Dr. Akira Matsuo (IMGSL)
←to ISSP TOP
The Institute for Solid State Physics,
5-1-5 Kashiwanoha Kashiwa-city, Chiba 277-8581 Japan