Effect of partial substitution of iso-valent Mo at Cr-site on electronic structure and physical properties of Fe2CrAl

TL;DR

This study explores how partial Mo substitution at the Cr site in Fe2CrAl affects its structural, magnetic, and electronic properties, revealing shifts in Curie temperature, suppression of cluster glass phase, and persistent Griffiths phase due to disorder.

Contribution

It provides new insights into how Mo substitution influences magnetic phases and properties in Fe2CrAl Heusler alloys, highlighting the role of anti-site disorder and hybridization effects.

Findings

Curie temperature decreases with Mo substitution

Cluster glass phase is suppressed at higher Mo concentrations

Griffiths phase persists above 350 K due to disorder

Abstract

Heusler alloy Fe2CrAl exhibits a ferromagnetic behaviour below Curie temperature (TC) ~ 202 K along with presence of cluster glass (CG) phase near freezing temperature (Tf) ~ 3.9 K and Griffiths phase (GP) above 300 K. The physical properties of this alloy are very sensitive to substitutions and anti-site disorder. Here, we investigate the effect of partial substitution of Mo at Cr-site on physical properties of Fe2CrAl. Structural and morphological analysis confirms the single cubic structure of the substituted alloys. Increment in Mo concentration shifts the TC towards lower temperature, which is ascribed to the effect of increased hybridization strength between 3d-4d states of Fe/Cr/Mo. Additionally, systematic analysis of AC susceptibility, magnetic memory effect and time dependent magnetization studies confirm the presence of CG-like phase near (Tf) ~ 3.5 K in Fe2Cr0.95Mo0.05Al. Such feature gets suppressed towards lower temperature with an increase of Mo concentration, i.e. below 1.8 K in Fe2Cr0.85Mo0.15Al. The origin of the glassy signature is ascribed to the decrement in magnetic anisotropy with Mo concentration. A partial increment in magnetic entropy change is also noted near TC with the increase in Mo substitution. Interestingly, at high temperatures (above 350 K), GP phase persists in both the alloys due to the presence of anti-site disorder.