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Quantum Fluctuations of a Nearly Critical Heisenberg Spin Glass

A. Georges·O. Parcollet·S. Sachdev
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Abstract

We describe the interplay of quantum and thermal fluctuations in the infinite-range Heisenberg spin glass. This model is generalized to SU(N) symmetry, and we describe the phase diagram as a function of the spin S and the temperature T. The model is solved in the large N limit and certain universal critical properties are shown to hold to all orders in 1/N. For large S, the ground state is a spin glass, but quantum effects are crucial in determining the low T thermodynamics: we find a specific heat linear in T and a local spectral density of spin excitations linear in frequency for a spin glass state which is marginally stable to fluctuations in the replicon modes. For small S, the spin-glass order is fragile, and a spin-liquid state dominates the properties over a significant range of temperatures and frequencies. We argue that the latter state may be relevant in understanding the properties of strongly-disordered transition metal and rare earth compounds.

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A. Georges, O. Parcollet, S. Sachdev. 2000-09-26. Quantum Fluctuations of a Nearly Critical Heisenberg Spin Glass. https://doi.org/10.1103/physrevb.63.134406

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