ISSP - The institute for Solid State Physics

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Otani Group
Professor
OTANI,
Yoshichika

Research Associate
ISSHIKI,
Hironari

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The concept of spin current, the flow of spin angular momentum, appeared in the end of 20th century. Spintronics has developed as a new approach which utilizes the combined function of charge current and spin current. The methods of generation, transmission and detection of spin current have been well established in the recent decade. The research of spintronics is entering a new phase, recently revealing new spin mediated-interconversions among quasi-particles in solid, such as electron, spin, phonon, photon and magnon etc. These “spin conversion” phenomena often manifest in the nano-scale region at simple interfaces of various materials, and thus, have great versatility and application possibility. Our fundamental research explores the new physics of spin conversion and clarifies their mechanisms. We also develop the spintronics devices in which a variety of spin conversion can be controlled, using nanofabrication techniques.

Estimation of the Rashba splitting in Non-Magnetic metal (NM)/bismuth oxide (Bi2O3) interface state. The magnitude and sign of the Rashba parameter at NM/Bi2O3 interface strongly depend on the NM (Cu, Ag, Au). This is the results of the modulation of the asymmetric feature of the charge density |ψ2| by the interface electric field Einter which is defined by the work function difference for NM and Bi2O3. (a) The schematics of NM/Bi2O3 interface and the Rashba splitting. (b) Spatial distribution of |ψ2| and electric potential V near the interface.
Spin-charge current conversion at molecule/metal interface observed by means of spin pumping method. Rashba splitting arises at carefully designed interface of lead (II) phthalocyanine (PbPc) and Cu. (a) The schematics of the PbPc/Cu interface. (b) The symmetric component of voltage signal (Vsym) attributed to the spin-charge current conversion at the interface as the function of the external magnetic field (Hres). The blue and red lines are for NiFe/Cu/PbPc and NiFe/Cu/H2Pc sample, respectively. A clear signal appears in the sample with PbPc/Cu interface.

Research Subjects

  1. Mechanisms of pure spin current generation and detection
  2. Magnetic phase transition by using spin current
  3. Spin-to-charge current conversion in the interface of topological insulator
  4. Molecular spintronics
  5. Spin injection into superconductor from ferromagnet