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Katsumoto Group

Research Associate

Research Associate

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With epitaxial growth of semiconductor and metallic films, and nano-fabrication techniques, we study quantum effects in low dimensional systems. Our research also spans some applications of the physics of electron and nuclear spins to so called spintronics. To expand the concept of quantum transport to spin degree of freedom, we have tried to create spin currents in quantum structures. A new type of magnetoresistnce is found in transport of spin polarized electrons injected from epitaxially grown Fe films into quantum well structures with strong spin-orbit interaction. A new method to obtain information on the dispersion relation of edge-magnetoplasmon in quantum Hall edge states has been developed. The method utilizes transmission of microwave through the two-dimensional electron gas, the area of which is controlled through the gate voltage. We expect the application to the fractional quantum Hall state with surface potential modulation.

Left: Color level plot of the magnetoresistance of a double quantum well device (InGaAs) with spin-orbit interaction as a function of field strength and angle from [110]. The sign is reversed around [100] (45º) and [010] (90º). Right: Polar plot of magnetoresistance amplitude for the in-plane field direction.
Grayscale plot of the gate bias Vg and frequency f dependence of the microwave transmission Δ. Edge-magnetoplasmon excitations are observed as peaks (lighter tone). Thick yellow curve in depicts calculated egde-magnetoplasmon excitation frequency vs. Vg for the fundamental mode.

Research Subjects

  1. Quantum transport in charge and spin freedoms
  2. Study of many-body effects in quantum structures
  3. Physics at interfaces between the phases with different symmetries