Electronic and magnetic properties of substitutional Mn clusters in (Ga,Mn)As

Abstract

The magnetization and hole distribution of Mn clusters in (Ga,Mn)As are investigated by all-electron total energy calculations using the projector augmented wave method within the density-functional formalism. It is found that the energetically most favorable clusters consist of Mn atoms surrounding one center As atom. As the Mn cluster grows the hole band at the Fermi level splits increasingly and the hole distribution gets increasingly localized at the center As atom. The hole distribution at large distances from the cluster does not depend significantly on the cluster size. As a consequence, the spin-flip energy differences of distant clusters are essentially independent of the cluster size. The Curie temperature $T_C$ is estimated directly from these spin-flip energies in the mean field approximation. When clusters are present estimated $T_C$ values are around 250 K independent of Mn concentration whereas for a uniform Mn distribution we estimate a $T_C$ of about 600 K.

7 pages, 5 figures, 2 tables; Revised manuscript 26. May 2005

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• Diffusion and clustering of substitutional Mn in (Ga,Mn)As
• Antiferromagnetic order in (Ga,Mn)N nanocrystals: A density functional theory study
• Carrier induced ferromagnetism in diluted local-moment systems
• First-principles calculations of the magnetic properties of (Cd,Mn)Te nanocrystals
• The influence of structural short-range order on the phase diagrams of diluted FCC magnet with arbitrary spin and modified RKKY interaction
• Optical spin control in nanocrystalline magnetic nanoswitches
• Effects of dilution and disorder on magnetism in diluted spin systems
• Out-of-plane magnetization reversal processes of (Ga,Mn)As with two different hole concentrations