Low temperature high magnetic field $^{57}Fe$ M$\ddot{o}$ssbauer study of kinetic arrest in $Hf_{0.77}Ta_{0.23}Fe_2$

TL;DR

This study uses low temperature high magnetic field $^{57}Fe$ M$ t{o}$ssbauer measurements to investigate kinetic arrest and magnetic phase transitions in $Hf_{0.77}Ta_{0.23}Fe_2$, revealing field-dependent ferromagnetic fractions and re-entrant transitions.

Contribution

It provides the first microscopic evidence of de-vitrification of kinetically arrested magnetic states using novel magnetic field protocols.

Findings

FM fraction increases with higher cooling magnetic field.

AFM spins cant and contribute to bulk magnetization under applied field.

Re-entrant transition observed during warming in high magnetic field.

Abstract

Low temperature high magnetic field $^{57}Fe$ M$\ddot{o}$ssbauer measurements were carried out on inter-metallic $Hf_{0.77}Ta_{0.23}Fe_2$ compound by following novel paths in H-T space. The ferromagnetic (FM) fraction at 5K and zero magnetic field is shown to depend on cooling field i.e., higher the field higher is the FM fraction. M$\ddot{o}$ssbauer spectra collected in the presence of 4 Tesla magnetic field shows that the antiferromagnetic (AFM) spins cant with respect to the applied magnetic field and hence, contribute to the total bulk magnetization in this compound. The data also show induced magnetic moment even at the 2a site of AFM phase. M$\ddot{o}$ssbauer spectra collected using CHUF (cooling and heating in un-equal magnetic fields) protocol shows re-entrant transition when sample is cooled in zero field and measured during warming in 4 Tesla showing FM state as the equilibrium state. The present work is the first microscopic experimental evidence for the de-vitrification of kinetically arrested magnetic state.