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arXiv · 1611.09752

Magnonic quantum Hall effect and Wiedemann-Franz law

Kouki Nakata·Jelena Klinovaja·Daniel Loss
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Abstract

We present a quantum Hall effect of magnons in two-dimensional clean insulating magnets at finite temperature. Through the Aharonov-Casher effect, a magnon moving in an electric field acquires a geometric phase and forms Landau levels in an electric field gradient of sawtooth form. At low temperatures, the lowest energy band being almost flat carries a Chern number associated with a Berry curvature. Appropriately defining the thermal conductance for bosons, we find that the magnon Hall conductances get quantized and show a universal thermomagnetic behavior, i.e., are independent of materials, and obey a Wiedemann-Franz law for magnon transport. We consider magnons with quadratic and linear (Dirac-like) dispersions. Finally, we show that our predictions are within experimental reach for ferromagnets and skyrmion lattices with current device and measurement techniques.

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Kouki Nakata, Jelena Klinovaja, Daniel Loss. 2017-03-04. Magnonic quantum Hall effect and Wiedemann-Franz law. https://doi.org/10.1103/physrevb.95.125429

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