Properties of a two-dimensional semimetal in a strong magnetic field |
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Authors: | é G Batyev |
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Institution: | (1) Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA |
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Abstract: | A system of two-dimensional electrons and holes ha s been investigated in a strong magnetic field, when it is sufficient to
take into account only the ground Landau level. It has been shown that the interaction of electrons and holes can lead to
an ordered state. In this problem, the exchange interaction in electron and hole subsystems is significant. The following
two cases have been considered: (a) there are one electron and one hole valleys, and at some magnetic field strength, there
exists an ordered state, as in an excitonic insulator; and (b) there exist one electron and two equivalent hole valleys (as
in the experiment performed by Kvon et al. 1]), and the hole system has an ordered state of the Stoner ferromagnetic type
in a specific range of magnetic field strengths. The spectra of elementary excitations of the Bose and Fermi types have been
obtained. The Fermi excitations have a gap in the energy spectrum, whereas the Bose excitations in the ordered states begin
with zero (to these excitations there corresponds an electric dipole moment). The self-consistent field approximation has
been used, which is exact when the numbers of electrons and holes are equal to each other. |
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Keywords: | |
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