Dresden 2009 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 4: II-VI semiconductors
HL 4.7: Vortrag
Montag, 23. März 2009, 12:00–12:15, POT 51
Accelerated, two-staged spin-lattice relaxation in (Zn,Mn)Se quantum wells — •Jörg Debus1, Vitalii Yu. Ivanov2, Andrei A. Maksimov3, Dmitri R. Yakovlev1, and Manfred Bayer1 — 1Experimentelle Physik II, Technische Universität Dortmund, 44221 Dortmund, Germany — 2Institute of Physics, Polish Academy of Sciences, 02668 Warsaw, Poland — 3Institute of Solid State Physics, Russian Academy of Sciences, 142432 Chernogolovka, Russia
The dynamics of spin-lattice relaxation of the Mn ions in (Zn,Mn)Se-based diluted magnetic semiconductor quantum wells with low Mn concentration (≤ 2%) is studied by time-resolved photoluminescence.
The quantum well magnetization is determined by single Mn ions as well as spin clusters with antiferromagnetically coupled Mn ions. Pair and triple clusters with next nearest neighbour ions acting as fast relaxing centers contribute to the energy transfer from the Mn system to the lattice via two-phonon Orbach transitions, resulting in a two-staged spin-lattice relaxation process. The efficiency of both processes is influenced by the Mn concentration, strength of applied magnetic field and optical excitation density.
A further impact of next nearest neighbour spin clusters on the spin-phonon interactions is revealed in cusps in the static and dynamic quantum well magnetization at specific magnetic fields below 10 T. The cusps correspond to an additional cooling of the Mn spin temperature due to a crossing of Zeeman-splitted cluster spin levels. Consequently, the emission of resonant phonons causes an acceleration of the spin-lattice relaxation.