Magnetic field induced modification of a first-order ferromagnetic transition in Eu2In

TL;DR

This study investigates how magnetic fields influence the first-order ferromagnetic transition in Eu₂In, revealing a complex two-step transition process without local structural changes.

Contribution

It demonstrates that the transition remains first order up to high fields and uncovers a field-induced splitting of the specific heat anomaly.

Findings

Magnetocaloric anomalies near 25 kOe suggest transition weakening.

Specific heat shows field-induced splitting of the anomaly.

EXAFS indicates no local structural change under magnetic field.

Abstract

We present a comprehensive study of the temperature- and magnetic-field-dependent magnetization, specific heat, and local crystal structure across the first-order ferromagnetic-paramagnetic transition in Eu$_2$In. Anomalies in the magnetocaloric response are observed near $H \approx 25$~kOe, including changes in field scaling of magnetic entropy, local entropy exponent, and universal master curve, which suggest an apparent weakening of the first-order character of the transition. However, quantitative analysis of the magnetocaloric parameters together with modified Arrott plots demonstrates that the transition remains first order up to at least 70~kOe. Specific-heat measurements reveal a field-induced splitting of the sharp zero-field anomaly into a doublet, providing a natural explanation for the change in the magnetocaloric response. Magnetic field dependent extended x-ray absorption fine structure (EXAFS) measurements show no detectable field-induced changes in the local coordination environment of Eu. We therefore attribute these observations to a magnetic field induced two-step transition process in Eu$_2$In.