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

Abstract

We report density-functional calculations of the ferromagnetic (FM) stabilization energy δ=E_FM−E_AFM 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.