Comparison of predicted ferromagnetic tendencies of Mn substituting the Ga site in III–V’s and in $I–III–VI2$ chalcopyrite semiconductors

We report density-functional calculations of the ferromagnetic (FM) stabilization energy $δ=EFM−EAFM$ for differently oriented Mn pairs in III–V’s (GaN, GaP, GaAs) and chalcopyrite $(CuGaS2,$ $CuGaSe2,$ $CuGaTe2)$ semiconductors. Ferromagnetism is found to be the universal ground state $(δ<0)$ in all cases. The order of FM stability in III–V’s is $GaN>GaP>GaAs,$ whereas in chalcopyrites it is $CuGaS2>CuGaSe2>CuGaTe2.$ Considering both groups, the order is $GaN→GaP→GaAs→CuGaS2→CuGaSe2→GaSb≈CuGaTe2.$ The stronger FM stabilization in III–V’s is attributed to the stronger covalent coupling between the Mn $3d$ and the anion $p$ orbitals. In contrast to expectations based on Ruderman–Kittel–(Kasuya)–Yosida, (i) all Mn–Mn pair separations show FM, with no FM to antiferromagnetic oscillations and, (ii) FM is orientationally dependent, with 〈110〉 Mn–Mn pairs being the most FM.