Journal ArticleDOI
Skyrmions and the crossover from the integer to fractional quantum Hall effect at small Zeeman energies
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It is found that the two-dimensional electron gas in a high magnetic field at filling factor ν=1 for an arbitrary ratio of the Zeeman energy gμ B B to the typical interaction energy always has a gap, even when the one-particle gap vanishes.Abstract:
We study the two-dimensional electron gas in a high magnetic field at filling factor \ensuremath{\nu}=1 for an arbitrary ratio of the Zeeman energy g${\mathrm{\ensuremath{\mu}}}_{\mathit{B}}$B to the typical interaction energy. We find that the system always has a gap, even when the one-particle gap vanishes, i.e., when g=0. When g is sufficiently large, the quasiparticles are perturbatively related to those in the noninteracting limit; we compute their energies to second order in the Coulomb interaction. For g smaller than a critical value ${\mathit{g}}_{\mathit{c}}$ the quasiparticles change character; in the limit of g\ensuremath{\rightarrow}0, they are skyrmions---spatially unbounded objects with infinite spin. In GaAs heterojunctions, the gap is unambiguously predominantly due to correlation effects; indeed, we tentatively conclude that g is always smaller than ${\mathit{g}}_{\mathit{c}}$, so the relevant quasiparticles are the skyrmions. The generalization to other odd-integer filling factors, and to \ensuremath{\nu}=1/3 and 1/5, is discussed.read more
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Topological properties and dynamics of magnetic skyrmions
TL;DR: From this description, potential applications of skyrmions as information carriers in magnetic information storage and processing devices are envisaged.
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Anomalous hall effect
TL;DR: In this paper, a review of experimental and theoretical studies of anomalous Hall effect (AHE), focusing on recent developments that have provided a more complete framework for understanding this subtle phenomenon and have, in many instances, replaced controversy by clarity.
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Real-space observation of a two-dimensional skyrmion crystal
X. Z. Yu,Yoshinori Onose,Naoya Kanazawa,Jin-Hong Park,Jung Hoon Han,Yoshio Matsui,Naoto Nagaosa,Yoshinori Tokura +7 more
TL;DR: Real-space imaging of a two-dimensional skyrmion lattice in a thin film of Fe0.5Co 0.5Si using Lorentz transmission electron microscopy reveals a controlled nanometre-scale spin topology, which may be useful in observing unconventional magneto-transport effects.
Journal ArticleDOI
Spontaneous skyrmion ground states in magnetic metals
TL;DR: It is theoretically shown that skyrmion textures may form spontaneously in condensed-matter systems with chiral interactions without the assistance of external fields or the proliferation of defects, within a phenomenological continuum model based on a few material-specific parameters that can be determined experimentally.
Journal ArticleDOI
Spontaneous atomic-scale magnetic skyrmion lattice in two dimensions
Stefan Heinze,Kirsten von Bergmann,Matthias Menzel,Jens Brede,André Kubetzka,Roland Wiesendanger,Gustav Bihlmayer,Stefan Blügel +7 more
TL;DR: In this article, a two-dimensional square lattice of skyrmions on the atomic length scale was described as the magnetic ground state of a hexagonal Fe film of one-atomic-layer thickness on the Ir(111) surface.