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arXiv · 0911.0995

Effect of random fluctuations on quantum spin-glass transitions at zero temperature

Kazutaka Takahashi·Yoshiki Matsuda
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Abstract

We study the effects of random fluctuations on quantum phase transitions by the energy gap analysis. For the infinite-ranged spin-glass models with a transverse field, we find that a strong sample-to-sample fluctuation effect leads to broad distributions of the energy gap. As a result, the linear, spin-glass, and nonlinear susceptibilities behave differently from each other. The power-law tail of the distribution implies a quantum Griffiths-like effect that could be observed in various random quantum systems. We also discuss the mechanisms of the phase transition in terms of the energy gap by comparing the Sherrington-Kirkpatrick model and random energy model, which demonstrate the difference between the continuous and discontinuous phase transitions.

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Kazutaka Takahashi, Yoshiki Matsuda. 2010-03-06. Effect of random fluctuations on quantum spin-glass transitions at zero temperature. https://doi.org/10.1143/jpsj.79.043712

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