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arXiv · 2604.05501

Valence Bond Glass and Glassy Spin Liquid in Disordered Frustrated Magnets

Soumyaranjan Dash·Vansh Narang·Sanjeev Kumar
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Abstract

The absence of conventional magnetic order together with anomalous low-temperature magnetic heat capacity is often interpreted as evidence for quantum spin liquid ground states in frustrated magnets. Using a recently developed semiclassical Monte Carlo approach, we show that similar thermodynamic signatures arise in the highly frustrated regime of the disordered spin-1/2 J1-J2 Heisenberg model on the square lattice. By analyzing the freezing parameters, the distribution of spin-spin correlations, and the specific heat, we identify the ground state as a valence-bond glass that melts into a glassy spin liquid at finite temperatures. We show that the low-temperature specific-heat anomaly originates from collective singlet excitations, and consequently it is insensitive to external magnetic fields. This leads to a robust experimental signature of the valence bond glass phase and a completely new interpretation of the thermodynamic data on disordered spin-liquid candidate materials.

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Soumyaranjan Dash, Vansh Narang, Sanjeev Kumar. 2026-04-07. Valence Bond Glass and Glassy Spin Liquid in Disordered Frustrated Magnets. https://arxiv.org/abs/2604.05501

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