Inverse magnetocaloric effect in synthetic antiferromagnets

TL;DR

This paper reports the experimental observation and theoretical explanation of an inverse magnetocaloric effect in synthetic antiferromagnets, where entropy increases upon switching from anti-parallel to parallel magnetic alignment near the Curie point.

Contribution

It introduces a microscopic model and simulations explaining the inverse effect, enabling design of tunable magnetocaloric materials for applications like magnetic refrigeration.

Findings

Inverse magnetocaloric effect observed experimentally.

The effect is explained by exchange interactions affecting the Curie temperature.

Potential for designing tunable magnetocaloric materials for spintronics and refrigeration.

Abstract

The magnetocaloric effect in exchange-coupled synthetic-antiferromagnet multilayers is investigated experimentally and theoretically. We observe a temperature-controlled inversion of the effect, where the entropy increases on switching the individual ferromagnetic layers from anti-parallel to parallel alignment near their Curie point. Using a microscopic analytical model as well as numerical atomistic-spin simulations of the system, we explain the observed effect as due to the interplay between the intra- and inter-layer exchange interactions, which either add up or counteract to effectively modulate the Curie temperature of the dilute ferromagnetic layers. The proposed method of designing tunable, strongly magneto-caloric materials should be of interest for such applications as heat-assisted spintronics and magnetic refrigeration.