Magnetocaloric effect in one-dimensional antiferromagnets

TL;DR

This paper investigates the magnetocaloric effect in one-dimensional quantum antiferromagnetic spin systems, revealing how magnetic fields induce significant entropy changes and cooling effects, especially in frustrated models, with implications for low-temperature refrigeration.

Contribution

It provides a detailed analysis of the magnetocaloric effect in various one-dimensional spin-1/2 models, highlighting the role of frustration and quantum phase transitions in cooling performance.

Findings

Temperature drops near quantum phase transitions during adiabatic processes.

More frustrated systems achieve lower temperatures upon adiabatic demagnetization.

Frustrated models retain finite entropy at zero temperature at specific magnetic fields.

Abstract

An external magnetic field induces large relative changes in the entropy of one-dimensional quantum spin systems at finite temperatures. This leads to a magnetocaloric effect, i.e. a change in temperature during an adiabatic (de)magnetization process. Several examples of one-dimensional spin-1/2 models are studied by employing the Jordan-Wigner transformation and exact diagonalization. During an adiabatic (de)magnetization process temperature drops in the vicinity of a field-induced zero-temperature quantum phase transition. Comparing different levels of frustration, we find that more frustrated systems cool down to lower temperatures. For geometrically frustrated spin models a finite entropy survives down to zero temperature at certain magnetic fields. This property suggests frustrated quantum spin systems as promising alternative refrigerant materials for low-temperature magnetic refrigeration.