Large Magnetic-Field-Induced Strain at the Magnetic Order Transition in Triangular Antiferromagnet AgCrS2

TL;DR

This study reveals that the triangular antiferromagnet AgCrS2 exhibits a large magnetic-field-induced strain of over 700 ppm at its Néel temperature, highlighting significant magnetoelastic coupling in antiferromagnets.

Contribution

It demonstrates a large, persistent magnetic-field-induced strain in AgCrS2, a rare phenomenon in antiferromagnets, and links it to phase coexistence at the magnetic transition.

Findings

AgCrS2 shows a large strain over 700 ppm at 42 K.

The strain is not reversible upon decreasing the magnetic field.

Similar but smaller effects observed in AuCrS2.

Abstract

Strain induced by a magnetic field is a common phenomenon for ferromagnets, but few antiferromagnets show large strain induced by a magnetic field. On the basis of linear strain measurements of sintered samples of triangular antiferromagnet ACrS2 (A = Cu, Ag, and Au) in magnetic fields up to 9 T, the AgCrS2 sample was found to show a large strain, yielding a large volume change over 700 ppm, which is one of the largest volume changes measured to date for an antiferromagnet. This large strain appeared only at the N\'eel temperature of 42 K and was not restored to its initial state when the applied magnetic field was decreased to zero; however, it was initialized by cooling the sample to far below the N\'eel temperature. These results suggest that the coexistence of magnetically ordered and paramagnetic phases at the first-order phase transition plays an important role. AuCrS2 showed a magnetic-field-induced strain with similar features, although it was smaller than that in AgCrS2.