Discovery and characterization of magnetism in sigma-phase intermetallic Fe-Re compounds

TL;DR

This study reveals that sigma-phase Fe-Re intermetallic compounds exhibit itinerant spin-glass magnetism with varying transition temperatures, combining experimental magnetometry and electronic structure calculations to characterize their magnetic behavior.

Contribution

It is the first comprehensive investigation combining experimental and theoretical methods to characterize magnetism in sigma-phase Fe-Re compounds.

Findings

All samples exhibit magnetism with transition temperatures between 65 K and 23 K.

Magnetism is itinerant and likely a heterogeneous spin-glass with re-entrant features.

Theoretical calculations show Fe atoms mainly contribute to magnetism, Re atoms have small moments.

Abstract

Systematic experimental (vibrating sample magnetometry) and theoretical (electronic structure calculations using charge and spin self-consistent Korringa-Kohn-Rostoker Green function method) studies were performed on a series of intermetallic sigma-phase Fe(100-x)Re(x) (x = 43-53) compounds. Clear evidence was found that all investigated samples exhibit magnetism with an ordering temperature ranging between 65 K for x = 43 and 23 K for x = 53. The magnetism was revealed to be itinerant and identified as a spin-glass (SG) possibly having a re-entrant character. The SG was found to be heterogeneous viz. two regimes could be distinguished as far as irreversibility in temperature dependence of magnetization is concerned: (1) of a weak irreversibility and (2) of a strong one. According to the theoretical calculations the main contribution to the magnetism comes from Fe atoms occupying all five sub lattices. Re atoms have rather small moments. However, the calculated average magnetic moments are highly (ferromagnetic ordering model) or moderately (antiparallel ordering model) overestimated relative to the experimental data.