Appearance of Half-Metallicity in the Quaternary Heusler Alloys

TL;DR

This paper uses first-principle calculations to show that quaternary Heusler alloys can exhibit half-metallicity across a range of compositions, with their magnetic properties following a linear Slater-Pauling rule.

Contribution

It demonstrates that intermediate compositions of certain quaternary Heusler alloys retain half-metallicity and follow a universal linear relation between total spin moment and valence electrons.

Findings

Half-metallicity persists across intermediate compositions.

Total spin moment scales linearly with valence electrons.

Atomic projected DOSs and spin moments reveal consistent trends.

Abstract

I report systematic first-principle calculations of the quaternary Heusler alloys like Co$_2$[Cr$_{1-x}$Mn$_x$]Al, Co$_2$Mn[Al$_{1-x}$Sn$_x$] and [Fe$_{1-x}$Co$_x$]$_2$MnAl. I show that when the two limiting cases (x=0 or 1) correspond to a half-metallic compound, so do the intermediate cases. Moreover the total spin moment $M_t$ in $\mu_B$ scales linearly with the total number of valence electrons $Z_t$ (and thus with the concentration $x$) following the relation $M_t=Z_t-24$, independently of the origin of the extra valence electrons, confirming the Slater-Pauling behavior of the normal Heusler alloys. Finally I discuss in all cases the trends in the atomic projected DOSs and in the atomic spin moments.