TY - JOUR
T1 - Finite-temperature magnetism in fractional quantum Hall systems
T2 - The composite-fermion Hartree-Fock approximation and beyond
AU - Murthy, Ganpathy
PY - 2000/12/18
Y1 - 2000/12/18
N2 - Using the Hamiltonian formulation for composite fermions developed recently, the temperature dependence of the spin polarization is computed for the translationally invariant fractional quantum Hall states at ν = 1/3 and ν = 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 ν = 1/3 lies above the experimental results for intermediate temperatures indicating the importance of long-wavelength spin fluctuations which are not correctly treated in the Hartree-Fock approximation. In the second step, spin fluctuations beyond the Hartree-Fock approximation are included for ν = 1/3 by mapping the problem onto the coarse-grained continuum quantum ferromagnet. The parameters of the description in terms of the effective continuum quantum ferromagnet 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.
AB - Using the Hamiltonian formulation for composite fermions developed recently, the temperature dependence of the spin polarization is computed for the translationally invariant fractional quantum Hall states at ν = 1/3 and ν = 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 ν = 1/3 lies above the experimental results for intermediate temperatures indicating the importance of long-wavelength spin fluctuations which are not correctly treated in the Hartree-Fock approximation. In the second step, spin fluctuations beyond the Hartree-Fock approximation are included for ν = 1/3 by mapping the problem onto the coarse-grained continuum quantum ferromagnet. The parameters of the description in terms of the effective continuum quantum ferromagnet 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.
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U2 - 10.1088/0953-8984/12/50/315
DO - 10.1088/0953-8984/12/50/315
M3 - Article
AN - SCOPUS:0034499675
SN - 0953-8984
VL - 12
SP - 10543
EP - 10560
JO - Journal of Physics Condensed Matter
JF - Journal of Physics Condensed Matter
IS - 50
ER -