ACTA

Ferromagnetic, Ferrimagnetic and Spin-wave Resonances in GaMnAs Layers

O. Fedorych^a, M. Byszewski^a,b, Z. Wilamowski^a,b, M. Potemski^b and J. Sadowski^a,b,c
^aInstitute of Physics, Polish Academy of Sciences, al. Lotników 32/46, 02-668 Warsaw, Poland
^bGrenoble High Magnetic Field Laboratory MPI CNRS, BP 166, 38042 Grenoble, France
^cOersted Laborartory, Copenhagen University, 2100 Copenhagen, Denmark
^dDepartment of Experimental Physics Chalmers University of Technology and Göteborg University, Sweden

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Molecular beam epitaxy grown Ga_1-xMn_xAs layers were investigated by means of magnetic resonances. With an increase in Mn concentration, x, the spectrum changes from the (i) paramagnetic one, with resolved fine and hyperfine structures, typical of S=5/2 spin of substitutional Mn²⁺ ions, for very diluted alloy, via (ii) paramagnetic spectrum, where the fine and hyperfine structures are averaged by a long range Mn²⁺-Mn²⁺ exchange coupling, (iii) single, isotropic line of ferromagnetic resonance. Insulator to metal transition is accompanied with occurrence of (iv) a very complex spectrum of the ferrimagnetic resonance, accompanied with the well-resolved spin wave resonance. Reentrance to insulator phase for the most condensed alloys is accompanied with the reentrance to (v) ferromagnetic phase. The data confirm that the effective mass holes transfer the exchange interaction between localized Mn²⁺ spins.

DOI: 10.12693/APhysPolA.102.617
PACS numbers: 71.55.Eq, 76.30.Fc, 75.50.Pp, 75.30.Gw