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arXiv · 1004.2221

Energy-gap analysis of quantum spin-glass transitions at zero temperature

Kazutaka Takahashi·Yoshiki Matsuda
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Abstract

We study for random quantum spin systems the energy gap between the ground and first excited states to clarify a relation to the spin-glass-paramagnetic phase transition. We find that for the transverse Sherrington-Kirkpatrick model the vanishing of the averaged gap does not identify the transition. A power-law form of the gap distribution function leads to power-law distributions of the linear, spin-glass, and nonlinear susceptibilities. They diverge at different points, which we attribute to a quantum Griffiths mechanism. On the other hand, the classical treatment is justified for the transverse random energy model and the phase transition can be found by a sudden change of the ground state.

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Kazutaka Takahashi, Yoshiki Matsuda. 2010-04-13. Energy-gap analysis of quantum spin-glass transitions at zero temperature. https://doi.org/10.1088/1742-6596%2F233%2F1%2F012008

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