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Takeyama Laboratory

Research Subjects
1: Technical developments for destructive ultra-high magnetic field magnets and for solid-state physics measurements
2: Magneto-optics in ultra-high magnetic fields
3: Magnetization processes of magnetic materials and the critical magnetic field in superconducting materials in ultra-high magnetic fields

 We are engaged in development for generating ultra-high magnetic fields above 100 T, and pursue the solid-state science realized under such an extreme condition. We employ two methods for the ultra-high magnetic field generation, one is the electro-magnetic flux compression (EMFC) and the other is the single-turn coil (STC) method. We have established a new type of coil for the EMFC, and currently the maximum magnetic field is 730 T. This value is the highest achieved thus far in an indoor setting in the world. Further development is underway for achieving much higher fields, more precise and reliable measurements for the solid-state physics. The horizontal and vertical (H- and V-) STCs are used for more precise measurements up to 300 T, respectively, in accordance with their magnetic field axes. The H-STC is mainly used for magneto-optical measurements by use of laser optics, whilst the V-STC is more suitable for the study of low-temperature magnetization in a cryogenic bath. We are conducting the studies on magneto-optics of carbon nano-materials or of semiconductor nano-structures as well as on the critical magnetic fields in superconducting materials and on the high-field magnetization processes of the magnetic materials with highly frustrated quantum spin systems.

Kindo Laboratory

Research Subjects
1: Study on magnetism of quantum spin systems
2: Study on magnetism and conductivity of strongly correlated electron systems
3: Development of non-destructive 100 T-magnet
4: Development of ultra-long pulse magnet

 We carry out precise measurements under non-destructive pulsed high magnetic fields that are generated by capacitor banks and flywheel DC generator installed at the facility. Various magnets have been developed at user’s requests. Up to now, available field conditions for users are as follows.
1. Short pulse magnet: Pulse duration 5 ms, maximum field 75 T
2. Mid pulse magnet: Pulse duration 30 ms, maximum field 65 T
Short pulse magnet is used mainly for magnetization measurements on insulating materials and Mid pulse magnet is used for various measurements on metallic materials. Our magnet has been breaking the world record of non-destructive mono-coil field and we continue to develop a new magnet aiming at the new world record of 100 T. We have installed the flywheel DC generator on May 2008. The generator enables us to generate longer pulsed field with the duration of 1-10 seconds. The Long pulsed fields can provide much better conditions for precise measurements that had been thought to be difficult before.

Tokunaga Laboratory

Research Subjects
1: Field-induced transitions in multiferroic materials
2: High-field studies on high temperature superconductors
3: High-speed polarizing microscope imaging in pulsed-high magnetic fields
4: Field-induced transitions in magnetic shape-memory alloys

 The crossed-coupling among spin, charge, orbital, and lattice degrees of freedom causes changes in various physical properties in magnetic fields. We study novel physical phenomena in these cross-correlated materials with utilizing the world highest class of pulsed magnetic fields. To capture the essential aspects of the composite phase transitions, we have been developed many experimental probes that can detect the instantaneous changes of various physical properties. In particular, our high-speed polarizing microscope system provides us with unique opportunity to visualize the changes in crystallographic symmetry in pulsed high magnetic fields. With utilizing these special instruments, we are studying on magnetoelectric effects in ferroelectric magnets, field-induced melting of spin/orbital order in a parent compound of the iron-based superconductors, and martensitic transformation in magnetic shape-recovery alloys.

Matsuda Laboratory

Research Subjects
1: Quest of magnetic field-induced phase transitions of solid oxygen
2: Magnetic field-induced insulator.metal transition
3: Magnetization process of quantum spin systems
4: Electronic states of heavy fermions in high magnetic fields

 We have been studying the electronic and magnetic properties of the matter in ultra-high magnetic fields exceeding 100 T in collaboration with Takeyama Group. Magnetic-field-induced phase transitions and cross over phenomena in strongly correlated systems are the main subjects.
Magnetic field can precisely control the electronic states through the Zeeman effect and Landau quantization. In ISSP, a 700-Tesla magnetic field is generated by the electro-magnetic flux compression method. Since the Zeeman energy in such a high field is larger than the energy corresponding to a room temperature, a significant field effect is expected. Specifically, the following subjects are studied: (1) Quest of magnetic fieldinduced phase transitions of solid oxygen, (2) Magnetic fieldinduced insulator.metal transition, (3) Magnetization process of quantum spin systems, and (4) Electronic states of heavy fermions in high magnetic fields. We also carry out the X-ray magneto-spectroscopy in pulsed high magnetic fields using synchrotron X-rays at the SPring-8 and KEK-PF. Elementand shell-selective X-ray magneto-spectroscopy is expected to uncover microscopic mechanisms of the magnetic-field-induced phenomena.

Osada Laboratory

Research Subjects
1: Quantum transport of Dirac electron system in graphene and zerogap organic conductors
2: Interlayer coherence and angle-dependent magnetotransport in layered conductors
3: Quantum transport of chiral surface state in multilayer quantum Hall systems
4: Charge and spin density waves under magnetic fields in low-dimensional organic conductors
5: Chaos and electron transport in Bloch electron systems under magnetic and electronic fields

 Transport study of low-dimensional electron system and/or Dirac fermion systems in solids. To search for new phenomena in electron systems with small spatial structures or internal degrees of freedom, to clarify their mechanisms, and to control them for application. We have a great interest in quantum effects, topological effects, and many-body effects, which relate to singularity of band structure, pseudo-spin internal degrees of freedom, and commensurability among electron orbital motions, vortex (magnetic flux) configuration, and spatial structures (topology). Our targets are low-dimensional conducting crystals such as graphene (monolayer graphite) and organic conductors, and artificial semiconductor/superconductor micro-structures fabricated by advanced processing techniques like MBE or EB. We flexibly explore new transport phenomena and electronic states by electric, magnetic, and thermal measurements using precise field rotation, miniature pulse magnet, MEMS probes, etc. under magnetic fields and low temperatures. Recently, we have concentrated our studies on quantum transport of relativistic Dirac electrons in graphene and organic conductors.


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The Institute for Solid State Physics, 5-1-5 Kashiwanoha Kashiwa-city, Chiba 277-8581 Japan