Electronic origins of the magnetic phase transitions in zinc-blende Mn chalcogenides

 

Su-Huai Wei and Alex Zunger

Phys. Rev. B 48, 6111 – Published 1 September 1993

 

Abstract

Precise first-principles spin-polarized total-energy and band-structure calculations have been performed for the zinc-blende Mn chalcogenides with the use of the local-spin-density (LSD) approach. We find that the LSD is capable of identifying the correct magnetic-ground-state structure, but it overestimates the ordering temperature $T_N$ and the valence-band exchange splitting ${\Delta }_x^p$. The discrepancy is attributed to the overestimation by LSD of the p-d coupling. Adjusting this coupling by an external potential and fitting its parameters to the s- and p-band exchange splitting in MnTe alone, we find that $T_N$=73, 90, and 128 K, respectively, for MnTe, MnSe, and MnS, in good agreement with experiment. This shows that the failures of the LSD in reproducing $T_N$ and ${\Delta }_x^p$ share a common physical origin, namely the overestimation of p-d coupling.

• Received 30 December 1992

DOI:https://doi.org/10.1103/PhysRevB.48.6111

©1993 American Physical Society

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