Phase stability of chromium based compensated ferrimagnets with inverse Heusler structure

TL;DR

This study evaluates the thermodynamic stability of chromium-based inverse Heusler compounds for spintronics, finding most are unstable or decompose into binary phases, with only Cr2FeSi and Cr2CoAl being stable against elemental decomposition.

Contribution

First comprehensive density functional theory assessment of stability for a range of Cr2YZ inverse Heusler compounds relevant to spintronics.

Findings

Cr2FeSi and Cr2CoAl are stable against elemental decomposition.

Most compounds are unstable or decompose into binary phases.

Binary decomposition pathways are identified for unstable compounds.

Abstract

Chromium based inverse Heusler compounds of the type Cr2YZ (Y=Co, Fe; Z=Al, Ga, In, Si, Ge, Sn) have been proposed as fully compensated half-metallic ferrimagnets. Such materials are of large interest for spintronics because they combine small magnetic moment with high spin polarization over a wide temperature range. We assess their thermodynamic stability by their formation enthalpies obtained from density functional theory calculations. All compounds under investigation are unstable. Cr2FeSi and Cr2CoAl are stable with respect to the elemental constituents, but decompose into binary phases. Cr2FeGe, Cr2CoGa, Cr2FeSn and Cr2CoIn are found to be unstable with respect to their elemental constituents. We identify possible binary decompositions.