2000/09/26 by A. Georges, O. Parcollet, S. Sachdev · 1 citation
Physics and Astronomy · #cond-mat.str-el #cond-mat.dis-nn
paper · pdf · doi:10.1103/physrevb.63.134406
published as Physical Review B 63, 134406 (2001) · 23 pages.Revtex4
arxiv created 2000/09/26 · arxiv updated 2009/11/30
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.