2013/06/21 by S. Stefanowicz, G. Kunert, C. Simserides +14
Chemistry · Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Chemistry #Condensed matter physics #Critical exponent #Crystallography #Curie temperature #Exponent #Ferromagnetism #Magnetic and transport properties of perovskites and related materials #Phase (matter) #Phase diagram #Phase transition #Physics #Quantum mechanics #Superexchange #ZnO doping and properties #cond-mat.dis-nn #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevb.88.081201
published as Phys. Rev. B 88, 081201(R) (2013) · 5 pages, 5 figures
arxiv created 2013/06/21 · openalex publication_date 2013/08/12 · arxiv updated 2013/11/15 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Molecular beam epitaxy has been employed to obtain Ga_1\ensuremath-xMnxN films with x up to 10% and Curie temperatures TC up to 13 K. The magnitudes of TC and their dependence on x, TC(x)\ensuremath∝xm, where m=2.2\ifmmode±\else\textpm\fi0.2, are quantitatively described by a tight-binding model of superexchange interactions and Monte Carlo simulations of TC. The critical behavior of this dilute magnetic insulator shows strong deviations from the magnetically clean case (x=1), in particular, (i) an apparent breakdown of the Harris criterion, (ii) a nonmonotonic crossover in the values of the susceptibility critical exponent \ensuremathγeff between the high temperature and critical regimes, and (iii) a smearing of the critical region, which can be explained either by the Griffiths effects or by macroscopic inhomogeneities in the spin distribution with a variance \ensuremathΔx=(0.2\ifmmode±\else\textpm\fi0.1)%.