ISSP - The institute for Solid State Physics

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Kohama Group
Associate Professor
KOHAMA,Yoshimitsu
Research Associate
NOMURA,
Toshihiro

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Ultra-high magnetic field (higher than 100 T) is an extreme condition that remains unexplored until recently. Many of unprecedented phenomena are expected to appear in ultra-high magnetic field region, and our group focuses on the observation/understanding of those exotic phenomena. To achieve this goal, we employ the following experimental techniques, “1. Magneto-optical measurement technique”, “2. Ultra-fast magnetoresistance measurement with micro-fabricated devices” and “3. High-field NMR experiment with a FPGA module”. With these techniques, we currently investigate the magnetotransport in topological insulators/superconductors and the novel magnetic phases in quantum spin systems. Our final goal is the condensed matter research at ultra-high magnetic field region up to ~1000 T, and thus our future work will also be devoted to technical developments for ultra-high magnetic field generations as well as the improvements of measurement techniques.

Zeeman splitting pattern of the R lines of Ruby. The non-linear Zeeman splitting was observed in ultra-high magnetic field region above 100 T. The inset shows the octahedrally coordinated Cr3+ ions in Al2O3 which is the cause of the photoluminescence of ruby.
Magnetoresistance of the upper critical field on Fe(Se,Te) superconductor. The upper critical field accompanied by the resistivity jump was observed around 40 T. The accessible field range for the magnetoresistance measurement is ~200 T.

Research Subjects

  1. Magneto-optical measurements with laser optics and its application to ultra-high magnetic field science
  2. NMR measurement under pulsed fields and its application to magnetic materials
  3. Development of new measurement techniques with nanofabrication technology
  4. Observation of quantum oscillation in ultra-high magnetic fields and fermiology of topological insulators