Geometric, electronic, and magnetic structure of Co$_2$FeSi: Curie temperature and magnetic moment measurements and calculations

TL;DR

This study investigates Co$_2$FeSi, revealing it has the highest magnetic moment and Curie temperature among Heusler compounds, supported by experimental measurements and electronic structure calculations.

Contribution

It combines experimental and theoretical methods to characterize Co$_2$FeSi, establishing its exceptional magnetic properties within Heusler compounds.

Findings

Co$_2$FeSi has a magnetic moment of 6μ_B.

It exhibits a Curie temperature of 1100K.

Supported by electronic structure calculations.

Abstract

In this work a simple concept was used for a systematic search for new materials with high spin polarization. It is based on two semi-empirical models. Firstly, the Slater-Pauling rule was used for estimation of the magnetic moment. This model is well supported by electronic structure calculations. The second model was found particularly for Co$_2$ based Heusler compounds when comparing their magnetic properties. It turned out that these compounds exhibit seemingly a linear dependence of the Curie temperature as function of the magnetic moment. Stimulated by these models, Co$_2$FeSi was revisited. The compound was investigated in detail concerning its geometrical and magnetic structure by means of X-ray diffraction, X-ray absorption and M\"o\ss bauer spectroscopies as well as high and low temperature magnetometry. The measurements revealed that it is, currently, the material with the highest magnetic moment ($6\mu_B$) and Curie-temperature (1100K) in the classes of Heusler compounds as well as half-metallic ferromagnets. The experimental findings are supported by detailed electronic structure calculations.