Research topics
>>Japanese
I am interested in many-body physics in two-dimensional electron systems (2DESs). In particular, I investigate electron spin states in a quantum Hall system by resistively-detected nuclear magnetic resonance. Recently, I started research on plasmon transport in GaAs/AlGaAs 2DESs or graphene using time-resolved transport measurement.


  • Plasmon transport in graphene and GaAs/AlGaAs 2DESs

  • Quantum Hall effect

  • Bilayer quantum Hall state at nu=1

  • Bilayer quantum Hall state at nu=2

  • Bilayer quantum Hall state at nu=2/3
    clear
    • Phase diagrams of nu=2 and nu=2/3 quantum Hall states in bilayer systems
      N. Kumada, D. Terasawa, M. Moriono, K. Tagashira, A. Sawada, E. F. Ezawa, K. Muraki, Y. Hirayama, and T. Saku
      Phys. Rev. B 69, 155319 (2004).
    Abstract--
    We compare QH states at nu=2 and its composite-fermion counterpart, nu =2/3, in bilayer systems with various tunneling gaps. By quantitative analyses, we conclude that composite-fermion interactions exert strong influence on the fractional QH states as electron interactions do on the integer QH states.

    • Phase diagram of interacting composite fermions in the bilayer nu=2/3 quantum Hall effect
      N. Kumada, D. Terasawa, Y. Shimoda, H. Azuhata, A. Sawada, E. F. Ezawa, K. Muraki, T. Saku, and Y. Hirayama
      Phys. Rev. Lett. 89, 116802 (2002).
    Abstract--
    We study the phase diagram of composite fermions in the presence of spin and pseudospin degrees of freedom in the bilayer nu=2/3 quantum Hall state. Quantitative analysis of the phase diagram provides information for interactions between composite fermions.
    The phase diagram is discussed in more detail in Phys. Rev. B 69, 155319 (2004).
    >>further information

  • Control of nuclear spins in semiconductors

  • Other topics