Light-induced topological magnons in two-dimensional van der Waals magnets
Driving a two-dimensional Mott insulator with circularly polarized light breaks time-reversal and inversion symmetry, which induces an optically-tunable synthetic scalar spin chirality interaction in the effective low-energy spin Hamiltonian. Here, we show that this mechanism can stabilize topologic...
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Veröffentlicht in: | SciPost physics 2020-10, Vol.9 (4), p.061, Article 061 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Driving a two-dimensional Mott insulator with circularly polarized
light breaks time-reversal and inversion symmetry, which induces an
optically-tunable synthetic scalar spin chirality interaction in the
effective low-energy spin Hamiltonian. Here, we show that this mechanism
can stabilize topological magnon excitations in honeycomb ferromagnets
and in optical lattices. We find that the irradiated quantum magnet is
described by a Haldane model for magnons that hosts
topologically-protected edge modes. We study the evolution of the magnon
spectrum in the Floquet regime and via time propagation of the magnon
Hamiltonian for a slowly varying pulse envelope. Compared to similar but
conceptually distinct driving schemes based on the Aharanov-Casher
effect, the dimensionless light-matter coupling parameter
\lambda = eEa/\hbar\omega
λ
=
e
E
a
/
ℏ
ω
at fixed electric field strength is enhanced by a factor
\sim 10^5
∼
10
5
.
This increase of the coupling parameter allows to induce a topological
gap of the order of
\Delta \approx 2
Δ
≈
2
meV with realistic laser pulses, bringing an experimental realization of
light-induced topological magnon edge states within reach. |
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ISSN: | 2542-4653 2542-4653 |
DOI: | 10.21468/SciPostPhys.9.4.061 |