Determination of the magnetic phase diagram in the H-T plane for a sigma-phase Fe47Mo53 alloy

TL;DR

This study maps the magnetic phase diagram of a sigma-phase Fe47Mo53 alloy by analyzing magnetization data under various conditions, revealing complex re-entrant magnetic transitions and characteristic temperature dependencies.

Contribution

It provides the first detailed magnetic phase diagram of this alloy, identifying multiple re-entrant transitions and their field dependence, with a novel power law description of characteristic temperature variations.

Findings

Double re-entrant transition PM-FM-AF-SG observed at H>50 Oe.

Single re-entrant transition PM-FM-SG observed at H<50 Oe.

Characteristic temperatures follow a power law with exponent 0.5(1).

Abstract

Magnetization measurements were carried out in the in field-cooled (FC) and in zero-field-cooled (ZFC) conditions versus temperature, T, and external magnetic field, H, on a sigma-phase Fe47Mo53 compound. Analysis of the measured M_FC and M_ZFC curves yielded values of characteristic temperatures: magnetic ordering (Curie) temperature, T_C, irreversibility temperature, T_ir, temperature of the maximum in M_ZFC, T_m, identified as the N\.eel (T_N) temperature, and cross-over temperature, T_co. Based on these temperatures a magnetic phase diagram in the H-T plane was outlined. The field dependences of the characteristic temperatures viz. of the irreversibility and of the cross-over temperatures were described in terms of a power law with the exponent 0.5(1). In the whole range of H i.e. up to 800 Oe, except the one H>50 Oe, a rare double re-entrant transition viz. PM-FM-AF-SG takes place. For small fields i.e. H<50 Oe a single re-entrant transition viz. PM-FM-SG is revealed.