Magnetic Grueneisen ratio of the random transverse-field Ising chain

TL;DR

This paper investigates the magnetic Gr"{u}neisen ratio in the one-dimensional random transverse-field Ising model, revealing its divergence and sign change at quantum criticality, thus confirming theoretical predictions through numerical simulations.

Contribution

It provides the first detailed numerical analysis of the magnetic Gr"{u}neisen parameter at the infinite-randomness quantum critical point in a disordered quantum spin chain.

Findings

Magnetic Gr"{u}neisen parameter diverges logarithmically in the Griffiths phase.

It changes sign exactly at the quantum critical point.

Results confirm predictions from strong-disorder renormalization group theory.

Abstract

The magnetic analog of the Gr\"{u}neisen parameter, i.e., the magnetocaloric effect, is a valuable tool for studying field-tuned quantum phase transitions. We determine the magnetic Gr\"{u}neisen parameter of the one-dimensional random transverse-field Ising model, focusing on its low-temperature behavior at the exotic infinite-randomness quantum critical point and in the associated quantum Griffiths phases. We present extensive numerical simulations showing that the magnetic Gr\"{u}neisen parameter diverges logarithmically with decreasing temperature in the quantum Griffiths phase. It changes sign right at criticality. These results confirm a recent strong-disorder renormalization group theory. We also compare our findings to the behavior of the clean transverse-field Ising chain.