Finite Temperature Magnetism in Fractional Quantum Hall Systems: Composite Fermion Hartree-Fock and Beyond

Abstract

Using the Hamiltonian formulation of Composite Fermions developed recently, the temperature dependence of the spin polarization is computed for the translationally invariant fractional quantum Hall states at $\nu =1/3$ and $\nu =2/5$ in two steps. In the first step, the effect of particle-hole excitations on the spin polarization is computed in a Composite Fermion Hartree-Fock approximation. The computed magnetization for $\nu =1/3$ lies above the experimental results for intermediate temperatures indicating the importance of long wavelength spin fluctuations which are not correctly treated in Hartree-Fock. In the second step, spin fluctuations beyond Hartree-Fock are included for $\nu =1/3$ by mapping the problem on to the coarse-grained continuum quantum ferromagnet. The parameters of the effective continuum quantum ferromagnet description are extracted from the preceding Hartree-Fock analysis. After the inclusion of spin fluctuations in a large-N approach, the results for the finite-temperature spin polarization are in quite good agreement with the experiments.

10 pages, 8 eps figures. Two references added

References in corpus (3)

• NMR Determination of 2D Electron Spin Polarization at $\nu =1/2$
• A Composite Fermion Hofstader Problem: Partially Polarized Density Wave States in the 2/5 FQHE
• Magnetic phenomena at and near nu =1/2 and 1/4: theory, experiment and interpretation

Cited by in corpus (6)

• Hamiltonian theory of fractionally filled Chern bands
• Hamiltonian theory of gaps, masses and polarization in quantum Hall states: full disclosure
• The $\nu =\frac{1}{2}$ Landau level: Half-full or half-empty?
• Hamiltonian theory of the half-filled Landau level with disorder: Application to recent NMR data
• Spin-excitations of the quantum Hall ferromagnet of composite fermions
• Hamiltonian Theory of Disorder at 1/3