Half metallicity in Cr substituted Fe2TiSn

S Chaudhuri,I Karaman,D Salas,P A Bhobe,V Srihari,E Welter

doi:10.1038/s41598-020-79895-7

Abstract

Band structure tailoring has been a great avenue to achieve the half-metallic electronic ground state in materials. Applying this approach to the full Heusler alloy Fe2TiSn, Cr is introduced systematically at Ti site that conforms to the chemical formula {text{Fe}}_{2} {text{Ti}}_{{1 - x}} {text{Cr}}_{x}Sn. Compositions so obtained have been investigated for its electronic, magnetic, and electrical transport properties with an aim to observe the half-metallic ferromagnetic ground state, anticipated theoretically for Fe2CrSn. Our experimental study using synchrotron X-ray diffraction reveals that only compositions with x le 0.25 yield phase pure L2_1 cubic structures. The non-magnetic ground state of Fe2TiSn gets dramatically affected upon inclusion of Cr giving rise to a localized magnetic moment in the background of Ruderman–Kittel–Kasuya–Yosida (RKKY) correlations. The ferromagnetic interactions begin to dominate for x = 0.25 composition. Results of its resistivity and magnetoresistance (MR) measurement point towards a half-metallic ground state. The calculation of exchange coupling parameter, hbox {J}_{{ij}}, and orbital projected density of states that indicate a change in hybridization between 3d and 5p orbital, support the observations made from the study of local crystal structure made using the extended X-ray absorption fine structure spectroscopy. Our findings here highlight an interesting prospect of finding half-metallicity via band structure tailoring for wide application in spintronics devices.

Highlights

Modern spintronic industry regards half-metallic materials with 100% spin polarization as the ideal candidates for device fabrication
The changing hybridization between constituent atoms is evident from the results of extended X-ray absorption fine structure (EXAFS) spectroscopy
The elemental ratios for each composition obtained from Energy Dispersive X-Ray (EDX) analysis match with the starting stoichiometry

Summary

Introduction

Modern spintronic industry regards half-metallic materials with 100% spin polarization as the ideal candidates for device fabrication. Among the full Heusler compositions predicted to be half-metallic, Co2MnSi is the most prominent candidate with Curie temperature as high as 1100 K, and sizeable magnetic moment ∼ 6 μB5. It is essential to note that the applicability of Heuslers is not limited to the field of spintronics alone These materials are known for a wide range of other properties like high thermopower generation, magnetic shape memory alloys, and a ctuators. Density functional theory(DFT) based first-principles calculations predict that F e2CrSn lies at a crossroad between a barely half-metallic state and a magnetic semiconductor. Density functional theory(DFT) based first-principles calculations predict that F e2CrSn lies at a crossroad between a barely half-metallic state and a magnetic semiconductor9 Such a unique band structure can give rise to fascinating transport and magnetic properties. The anomalously linear and positive variation of low temperature MR in Fe2Ti0.75Cr0.25 Sn is the notable signature of its half-metallic ground state

Methods

Results

Conclusion