Quantum phase transition in a disordered long-range transverse Ising antiferromagnet

TL;DR

This paper investigates the quantum phase transitions in a disordered long-range transverse Ising antiferromagnet, revealing how disorder and quantum fluctuations influence the stability of antiferromagnetic and spin glass phases.

Contribution

It provides the first detailed phase diagrams for the disordered long-range transverse Ising antiferromagnet, combining analytical and Monte Carlo methods to explore disorder-induced glass phases.

Findings

Antiferromagnetic order is immediately broken by quantum or thermal fluctuations.

Infinitesimal SK disorder induces a stable spin glass phase in the system.

Transition from glass to paramagnetic phase occurs at higher fluctuations.

Abstract

We consider a long-range Ising antiferromagnet put in a transverse field (LRTIAF) with disorder. We have obtained the phase diagrams for both the classical and quantum case. For the pure case applying quantum Monte Carlo method, we study the variation of order parameter (spin correlation in the Trotter direction), susceptibility and average energy of the system for various values of the transverse field at different temperatures. The antiferromagnetic order is seen to get immediately broken as soon as the thermal or quantum fluctuations are added. We discuss generally the phase diagram for the same LRTIAF model with perturbative Sherrington-Kirkpatrick (SK) type disorder. We find that while the antiferromagnetic order is immediately broken as one adds an infinitesimal transverse field or thermal fluctuation to the pure LRTIAF system, an infinitesimal SK spin glass disorder is enough to induce a stable glass order in the LRTIAF. This glass order eventually gets destroyed as the thermal or quantum fluctuations are increased beyond their threshold values and the transition to para phase occurs. Analytical studies for the phase transitions are discussed in detail in each case. These transitions have been confirmed by applying classical and quantum Monte Carlo methods. We show here that the disordered LRTIAF has a surrogate incubation property of the SK spin glass phase.