Dresden 2017 – scientific programme
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MA: Fachverband Magnetismus
MA 38: Electron Theory of Magnetism and Correlations
MA 38.6: Talk
Wednesday, March 22, 2017, 11:00–11:15, HSZ 403
Coherence and stiffness of spin waves in diluted ferromagnets — •Ilja Turek1, Josef Kudrnovsky2, and Vaclav Drchal2 — 1Institute of Physics of Materials, Acad. Sci. Czech Rep., Brno, Czech Republic — 2Institute of Physics, Acad. Sci. Czech Rep., Prague, Czech Republic
We present results of a numerical analysis of magnon spectra in supercells simulating low-dimensional and bulk random diluted ferromagnets with long-ranged pair exchange interactions [1]. We show that low-energy spectral regions for these strongly disordered systems contain a coherent component leading to interference phenomena manifested by a pronounced sensitivity of the lowest excitation energies to the adopted boundary conditions. The dependence of configuration averages of these excitation energies on the supercell size can be used for an efficient determination of the spin-wave stiffness D. The developed formalism is applied to the ferromagnetic Mn-doped GaAs semiconductor with optional incorporation of phosphorus; the obtained concentration trends of D are found in reasonable agreement with recent experiments. Moreover, a relation of D to the Curie temperature has been studied for Mn-doped GaAs and GaN semiconductors.
[1] I. Turek et al., arXiv: 1611.06691 (2016).