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arXiv · 2509.07062

Transient localization from fractionalization: vanishingly small heat conductivity in gapless quantum magnets

Shi Feng·Penghao Zhu·Johannes Knolle·Michael Knap
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Abstract

Several candidate materials for gapless quantum spin liquids exhibit a vanishing thermal conductivity, which is at odds with theoretical predictions. Here, we show that a suppressed response can arise due to transient localization from fractionalization, even in the absence of extrinsic defects or disorder. Concretely, we consider a Kitaev ladder model in a uniform magnetic field, whose spin degrees of freedom fractionalize into visons and spinons. For moderate magnetic fields, visons are heavy and act as quasi-static disorder that induce transient localization of light spinons even in the translation-invariant model and at zero temperature, which strongly suppresses the residual conductivity at finite but low frequencies. At ultralow frequencies the conductivity is restored; however, such scales can be extremely hard to reach in experiments. Our results identify transient localization as a signature of fractionalization and provide a framework for interpreting anomalous transport in gapless spin liquid candidates.

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Shi Feng, Penghao Zhu, Johannes Knolle, Michael Knap. 2025-09-26. Transient localization from fractionalization: vanishingly small heat conductivity in gapless quantum magnets. https://arxiv.org/abs/2509.07062

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