Structure, magnetism and magnetic compensation behavior of Co50-xMn25Ga25+x and Co50-xMn25+xGa25 Heusler alloys

TL;DR

This study systematically investigates the structure, magnetism, and electronic properties of Co-Mn-Ga Heusler alloys, revealing complex magnetic behaviors and the influence of composition on their magnetic and structural characteristics.

Contribution

It provides new insights into the magnetic competition, electronic structure, and magnetic compensation behavior in Co-Mn-Ga Heusler alloys through combined experimental and first-principles approaches.

Findings

All samples exhibit body centered cubic structures with high atomic order.

Magnetic competition causes a dramatic decrease in Curie temperature and magnetic moment compensation.

Electronic structure suggests coexistence of itinerant and localized magnetism.

Abstract

The structure, magnetism, magnetic compensation behavior, exchange interaction and electronic structures of Co50-xMn25Ga25+x and Co50-xMn25+xGa25 (x=0-25) alloys have been systematically investigated by both experiments and first-principles calculations. We found that all the samples exhibited body centered cubic structures with a high degree of atomic ordering. With increasing Ga content, the composition dependence of lattice parameters shows a kink point at the middle composition in Co50-xMn25Ga25+x alloys, which can be attributed to the enhanced covalent effect between the Ga and the transition metals. Furthermore, a complicated magnetic competition has been revealed in Co50-xMn25Ga25+x alloys, which causes the Curie temperature dramatically decrease and results in a magnetic moment compensation behavior. In Co50-xMn25+xGa25 alloys, however, with increasing Mn content, an additional ferrimagnetic configuration was established in the native ferromagnetic matrix, which causes the molecular moment monotonously decreases and the exchange interaction enhances gradually. The electronic structure calculations indicate that the Co50-xMn25+xGa25 alloys are likely to be in a coexistence state of the itinerant and localized magnetism. Our study will be helpful to understand the nature of magnetic ordering as well as to tune magnetic compensation and electronic properties of Heusler alloys.