Disorder in Diluted Spin Systems

Abstract

The influence of substitutional disorder on the magnetic properties of diluted Heisenberg spin systems is studied with regard to the magnetic stability of ferromagnetic diluted semiconductors (DMS). The equation of motion for the magnon Green's function within Tyablikov approximation is solved numerically for finite systems. The resulting spectral density is then used to estimate the magnetization and Curie temperature of an infinite system. This method is suitable for any form of a ferromagnetic exchange interaction. Besides different lattices and spin magnitude $S$, exchange interactions of different range are examined. The results show that, for short-range interaction, no magnetic order exists below the critical percolation concentration, whereas a linear dependence of the Curie temperature on the concentration of spins is found for ferromagnetic long-range interaction.

9 pages, 6 figures

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• Spinodal nanodecomposition in magnetically doped semiconductors
• Ferromagnetism in Nitrogen-doped MgO
• New High-$T_c$ Half-Heusler Ferromagnets NiMnZ (Z = Si, P, Ge, As)
• Magnetism in (III, Mn)-V Diluted Magnetic Semiconductors: Effective Heisenberg Model
• Carrier induced ferromagnetism in diluted local-moment systems
• Properties of group-IV-based ferromagnetic semiconductor GeFe: Growth temperature dependence, lattice constant, location of Fe atoms, and their relevance to the magnetic properties
• Spin dynamics in the diluted ferromagnetic Kondo lattice model
• Effects of dilution and disorder on magnetism in diluted spin systems
• Disordered Correlated Kondo-lattice model
• Coherence and stiffness of spin waves in diluted ferromagnets
• Curie temperatures of the concentrated and diluted Kondo-lattice model as a possible candidate to describe magnetic semiconductors and metals
• Spin-wave theory in a randomly disordered lattice: A Heisenberg ferromagnet