Nobuki Maeda

Compressible anisotropic states around the half-filled Landau levels

Using the von Neumann lattice formalism, we study compressible anisotropic states around the half-filled Landau levels in the quantum Hall system. In these states the unidirectional charge-density wave (UCDW) state seems to be the most plausible state. The charge-density profile and Hartree-Fock energy of the UCDW are calculated self-consistently. The wavelength dependence of the energy for the UCDW is also obtained numerically. We show that the UCDW is regarded as a collection of the one-dimensional lattice Fermi-gas systems which extend to the uniform direction. The kinetic energy of the gas system is generated dynamically from the Coulomb interaction.

DUALITY RELATION AMONG PERIODIC-POTENTIAL PROBLEMS IN THE LOWEST LANDAU LEVEL

Using a momentum representation of a magnetic von Neumann lattice, we study a two-dimensional electron in a uniform magnetic field and obtain one-particle spectra of various periodic short-range potential problems in the lowest Landau level.We find that the energy spectra satisfy a duality relation between a period of the potential and a magnetic length. The energy spectra consist of the Hofstadter-type bands and flat bands. We also study the connection between a periodic short-range potential problem and a tight-binding model.

STABILITY OF THE COMPRESSIBLE QUANTUM HALL STATE AROUND THE HALF-FILLED LANDAU LEVEL

We study the compressible states in the quantum Hall system using a mean field theory on the von Neumann lattice. In the lowest Landau level, a kinetic energy is generated dynamically from Coulomb interaction. The compressibility of the state is calculated as a function of the filling factor

Field theory on the von Neumann lattice and the quantized Hall conductance of Bloch electrons

\nu

The London Equation in Quantum Spin Hall System with Electronic Correlation

and the width

Optimal orientation of striped states in the quantum Hall system against external modulations

d

Effective Hamiltonian for striped and paired states at the half-filled Landau level

of the spacer between the charge carrier layer and dopants. The compressibility becomes negative below a critical value of

Anisotropic ground states of the quantum Hall system with currents

d

Energy spectrum of neutral collective excitations in striped Hall states

and the state becomes unstable at

Pressure, resistance, and current activation of anisotropic compressible Hall states

\nu=1/2