Magnetic ordering above room temperature in the sigma-phase of Fe66V34

TL;DR

This study demonstrates that sigma-phase Fe-V alloys exhibit magnetic ordering above room temperature, with the highest Curie temperature reaching 315.5 K, and reveals strong correlations among magnetic properties.

Contribution

It provides new experimental data on magnetic properties of Fe-V sigma-phase alloys, especially showing magnetic ordering above room temperature and detailed correlations among magnetic quantities.

Findings

Maximum Curie temperature of 315.5 K in Fe-V sigma-phase.

Strong linear correlation between Curie temperature and magnetic moment.

Hyperfine field correlates with magnetic moment with a coupling constant.

Abstract

Magnetic properties of four sigma-phase Fe_(100-x)V_x samples with 34.4<x<55.1 were investigated by Mossbauer spectroscopy and magnetic measurements in the temperature interval 5-300 K. Four magnetic quantities viz. hyperfine field, Curie temperature, magnetic moment and susceptibility were determined. The sample containing 34.4 at% V was revealed to exhibit the largest values found up to now for the sigma-phase for average hyperfine field, B = 12.1 T, average magnetic moment per Fe atom, m = 0.89 mB, and Curie temperature, TC = 315.5 K. The quantities were shown to be strongly correlated with each other. In particular, TC is linearly correlated with m with a slope of 406.5 K/mB, as well as B is so correlated with m yielding 14.3 T/mB for the hyperfine coupling constant.