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arXiv:2603.11186

Hall conductance in a weakly time-reversal invariant open system

Alexander Fagerlund, Christopher Ekman, Rodrigo Arouca

cond-mat.mes-hallcond-mat.quant-gascond-mat.str-elquant-phSubmitted Mar 11, 2026• Announced Mar 13, 2026
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Abstract

The quantum Hall effect and the quantum anomalous Hall effect both require time-reversal invariance to be broken. We show that non-equilibrium effects can cause Hall physics to arise even when the system is weakly time-reversal symmetric and no magnetic field is applied. In our model, this occurs due to a fermionic subsystem breaking time-reversal invariance even if the system as a whole does not. The fermions receive a TRI-breaking self-energy, caused by interactions with bosonic degrees of freedom in the system and with an external reservoir. As a result, the fermions develop a non-quantized Hall conductance. We demonstrate that, unlike in the equilibrium case, the presence of a mass term is insufficient for the Hall conductance to appear, and wave-function renormalization effects have to be included.

Comments
11+9 pages, 2+2 figures

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