Critical properties of quantum spin systems at zero temperature

Subir Sachdev A

Amnon Aharony A, Yuval Gefen, Yonathan Shapir

The critical properties of d-dimensional zero-temperature quantum-mechanical spin models are studied in the presence of random fields, and shown to be the same as those of the zero random field case in (d-3) dimensions. These properties are also the same as those of the classical transition, occurring at finite temperatures. Random fields thus destroy the quantum to classical crossover near zero temperature.

Qing Jiang, Z. Y. Li

In this paper we suggest a method that combines the effective-field renormalization group with the discretized path-integral method to study the critical behavior of the transverse Ising model in a quantum-spin system. We find the results on a critical transverse field and critical exponent at zero temperature to be closely comparable to other results. This demonstrates the utility of this method in studying critical properties of quantum-spin systems.

В. М. Конторович, V. M. Tsukernik

L V T Tavares, L G dos Santos, G T Landi +2 more

Abstract This work is dedicated to the study of a supersymmetric quantum spherical spin system with short-range interactions. We examine the critical properties both a zero and finite temperature. The model undergoes a quantum phase transition at zero temperature without breaking supersymmetry. At finite temperature the supersymmetry is broken and the system exhibits a thermal phase transition. We determine the critical dimensions and compute critical exponents. In particular, we find that the model is characterized by a dynamical critical exponent z = 2. We also investigate properties of correlations in the one-dimensional lattice. Finally, we explore the connection with a nonrelativistic version of the supersymmetric nonlinear sigma model and show that it is equivalent to the system of spherical spins in the large N limit.

Marek Biskup, Lincoln Chayes, Shannon Starr