Massive spin-flip excitations in a $\nu = 2$ quantum Hall ferromagnet
| Autor: | Dickmann, S., Berezhnoy, P. S. |
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| Rok vydání: | 2023 |
| Předmět: | |
| Zdroj: | Phys. Rev. B 108, 115313 (2023) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.108.115313 |
| Popis: | Excitation with a massive spin reversal of the individual skyrmion/antiskyrmion type is theoretically studied in a quantum Hall ferromagnet, where the zero and first Landau levels are completely occupied only by electrons with spins aligned strictly in the direction determined by the magnetic field. The Wigner-Seitz parameter is not necessarily considered to be small. The microscopic model in use is based on a reduced basic set of quantum states [the so-called ''single-mode (single-exciton) approximation''], which allows proper account to be taken for mixing of Landau levels, and substantiating the equations of the classical $O(3)$ nonlinear $\sigma$ model. The calculated ''spin stiffness'' determines the exchange gap for creating a pair of skyrmion and antiskyrmion. This gap is significantly smaller than the doubled cyclotron energy and the characteristic electron-electron correlation energy. Besides, the skyrmion--antiskyrmion creation gap is much smaller than the energy of creation of a separated electron--exchange-hole pair calculated in the limit case of a spin magnetoexciton corresponding to an infinitely large 2D momentum. At a certain magnetic field (related to the 2D electron density in the case of fixed filling factor $\nu$), the gap vanishes, which presumably points to a Stoner transition of the quantum Hall ferromagnet to a paramagnetic phase. Comment: 9 pages, 1 figures |
| Databáze: | arXiv |
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