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HL: Halbleiterphysik
HL 15: Quanten-Hall-Effekt
HL 15.4: Vortrag
Dienstag, 27. März 2001, 11:15–11:30, S16
Composite Fermions with Spin: ground state polarization and activation gap — •Eros Mariani1, Maura Sassetti2, and Bernhard Kramer1 — 1I Institut fuer Theoretische Physik, Universitaet Hamburg, Jungiusstrasse 9, D-20355 Hamburg, Germany — 2Dipartimento di Fisica, INFM, Universita’ di Genova, Via Dodecaneso 33, I-16146 Genova, Italy
The degree of spin polarization γe of the FQHE ground state at fixed filling factors ν is analyzed within a mean field approximation for spinful composite fermions (CF). By varying the magnetic field B several phase transitions between differently polarized ground states are predicted, in excellent agreement with recent experimental measurements [1]. Including spin-orbit coupling between different CF Landau levels yields the zero temperature smoothening of γe around the phase transition points. Additional semiquantitative predictions for the activation gap as a function of B are made. These are in good agreement with analogous experimental studies at ν=2/3 and 8/5 [2,3].
[1] I. V. Kukushkin et al., Phys. Rev. Lett. 82, 3665 (1999) [2] J. P. Eisenstein et al., Phys. Rev. Lett. 62, 1540 (1989) [3] J. P. Eisenstein et al., Phys. Rev. B 41, 7910 (1990)