Specific heat behavior in finite-sized Lipkin-Meshkov-Glick spin system

Abstract

A quantum heat engine whose working substance is described by the Lipkin-Meshkov-Glick (LMG) model has been shown to improve its efficiency when the LMG system is near its quantum phase transition. It is of interest to know how the specific heat of such an engine will behave under similar conditions. Therefore, in this work, we construct the specific heat curves of the LMG spin system consisting of spin-1/2 particles in a plane of sizes N = 2, 4, 6, 8. Effects of the field strength, temperature, and system size on the specific heat are analyzed. Salient features of the specific heat curve as a function of field strength are observed in relation to the ground state degeneracy that occurs in key field strength values.