title: 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 (DMS) 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 4μ(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.
authors.affiliation: Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA.|Center for Computation and Technology, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
authors.forename: Ryky
authors.initials: R
authors.lastname: Nelson
authors.affiliation: Center for Nanophase Materials Sciences and Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: Tom
authors.initials: T
authors.lastname: Berlijn
authors.affiliation: Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA.|Center for Computation and Technology, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
authors.forename: Juana
authors.initials: J
authors.lastname: Moreno
authors.affiliation: Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA.|Center for Computation and Technology, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Jarrell
authors.affiliation: Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA.|Physics Department, State University of New York, Stony Brook, New York 11790, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Ku