What is the valence of Mn in Ga${}_{1-x}$Mn${}_x$N?

Abstract

We investigate the current debate on the Mn valence in Ga${}_{1-x}$Mn${}_x$N, a diluted magnetic semiconductor (DMSs) with a potentially high Curie temperature. From a first-principles Wannier-function analysis, we unambiguously find the Mn valence to be close to $2+$ ($d^5$), but in a mixed spin configuration with average magnetic moments of 4${\mu }_B$. By integrating out high-energy degrees of freedom differently, we further derive for the first time from first-principles two low-energy pictures that reflect the intrinsic dual nature of the doped holes in the DMS: 1) an effective $d^4$ picture ideal for local physics, and 2) an effective $d^5$ picture suitable for extended properties. In the latter, our results further reveal a few novel physical effects, and pave the way for future realistic studies of magnetism. Our study not only resolves one of the outstanding key controversies of the field, but also exemplifies the general need for multiple effective descriptions to account for the rich low-energy physics in many-body systems in general.

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Cited by in corpus (5)

• Systematic Quantum Cluster Typical Medium Method For the Study of Localization in Strongly Disordered Electronic Systems
• Generalized Multiband Typical Medium Dynamical Cluster Approximation: Application to (Ga,Mn)N
• Valence, exchange interaction, and location of Mn in polycrystalline Mn(x)Ga(1-x)N (x<0.04)
• Exchange coupling and Mn valency in GaN doped with Mn and co-doped with Mg
• `Interaction annealing' to determine effective quantized valence and orbital structure: an illustration with ferro-orbital order in WTe${}_2$