The dynamics of spin-lattice relaxation of the Mn-ions in (Zn,Mn)Se-based diluted-magnetic-semiconductor quantum wells is studied by time-resolved photoluminescence.The spin-lattice relaxation time varies by five orders of magnitude from 10 -3 down to 10 -8 s, when the Mn content increases from 0.4 up to 11%. Free carriers play an important role in this dynamics. Hot carriers with excess kinetic energy contribute to heating of the Mn system, while cooling of the Mn system occurs in the presence of cold background carriers provided by modulation doping. In a Zn 0.89 Mn 0.11 Se quantum well structure, where the spin-lattice relaxation process is considerably shorter than the characteristic lifetime of nonequilibrium phonons, also the phonon dynamics and its contribution to heating of the Mn system are investigated.PACS: 75.50. Pp, 78.55.Et, 78.20.Ls, 2

The technological concept of "digital alloying" offered by molecular-beam epitaxy is demonstrated to be a very effective tool for tailoring static and dynamic magnetic properties of diluted magnetic semiconductors. Compared to common "disordered alloys" with the same Mn concentration, the spin-lattice relaxation dynamics of magnetic Mn ions has been accelerated by an order of magnitude in (Cd,Mn)Te digital alloys, without any noticeable change in the giant Zeeman spin splitting of excitonic states, i.e. without effect on the static magnetization. The strong sensitivity of the magnetization dynamics to clustering of the Mn ions opens a new degree of freedom for spin engineering. PACS: 75.50.Pp, 78.55.Et, 78.20.Ls, 85.75.-d II-VI diluted magnetic semiconductors (DMS) like (Cd,Mn)Te or (Zn,Mn)Se are well-known model materials for testing spintronic concepts [1]. A variety of magneto-optical and magnetotransport effects originates from the strong exchange interaction of free carriers with localized magnetic moments of Mn 2+ ions [2]. The magnetic properties of the Mn ion system, which depend

The dynamical response of magnetic ion system to pulsed laser excitation is studied in ͑Zn, Mn͒Se/ ͑Zn, Be͒Se and ͑Cd, Mn͒Te/ ͑Cd, Mg͒Te quantum well structures. Contributions of a direct heating of the Mn system by photocarriers and an indirect heating via nonequilibrium phonons are distinguished. Their relative efficiency is measured at different excitation densities and over a wide range of Mn concentrations from 0.4 to 11%. For all studied regimes the direct energy transfer from carriers dominates in ͑Zn,Mn͒Se structures. In ͑Cd,Mn͒Te structures a regime where the direct heating is still prominent but weaker than the phonon contribution is found.

The multiferroic rare-earth compounds RMnO3 with R=Ho–Yb are shown to be the source of “gigantic” magnetoelectric effects. Application of static magnetic or electric field induces a phase transition with antiferromagnetic reordering of the Mn3+ sublattice and ferromagnetic ordering in the rare-earth sublattices. An imbalance of the Mn3+–R3+ superexchange induced by the ferroelectric distortion is revealed as the microscopic origin of the magnetoelectric effect.

We show that the magnetization dynamics in diluted magnetic semiconductors can be controlled separately from the static magnetization by means of an electric field. It is important for applications based on DMS to control static and dynamic magnetic properties separately. In II-VI DMS the static and dynamic properties of the Mn spin system

The effects of microwave radiation with a frequency of 60 GHz on the magneto-optical properties of diluted magnetic semiconductors are studied on ͑Zn,Mn͒Se/͑Zn,Be͒Se quantum wells. Resonant heating of the Mn 2+ ions leads to an increase in the Mn-spin temperature as detected by the shift of emission line and increase in emission intensity. Nonresonant heating mediated by free carriers is also observed through variation in the polarization degree of emission. The mechanisms of optically detected magnetic resonance in diluted magnetic semiconductors are discussed.

In this paper we give a brief overview of our studies on dynamical processes in diluted-magneticsemiconductor heterostructures based on (Zn,Mn)Se and (Cd,Mn)Te. Presence of free carriers is an important factor which determines the energy-and spin transfer in a coupled systems of magnetic ions, lattice (the phonon system) and carriers. We report also new data on dynamical response of magnetic ions interacting with photogenerated electron-hole plasma. (Zn,Mn)Se/(Zn,Be)Se structures with relatively high Mn content of 11% provide spin-lattice relaxation time of about 20 ns, which is considerably shorter then the characterictic times of nonequilibrium phonons ranging to 1 µs. s.1 Introduction Magnetic, optical and transport properties of heterostructures based on diluted magnetic semiconductors (DMS), which are treated nowadays as model structures for spintronic devices, are determined by coupled systems of magnetic ions, lattice (the phonon system) and free carriers. Presence of free carriers (their concentration, temperature and spin polarization) is of great importance for static characteristics and dynamical properties of DMS materials as it modifies strongly efficiency of energyand spin transfer between the systems of DMS heterostructures.In our studies we are using an internal thermometer, which is provided by the high sensitivity of the giant Zeeman splitting of excitons (band states) to the polarization of the magnetic Mn ions. This allows us to detect with high accuracy the temperature (or temperature variation) of the Mn system. We exploit different ways of injecting energy into DMS structures in order to check the efficiency of linking channels between the lattice, the magnetic-ion system and free carriers (see Fig. 1). Dealing with a temperature of the Mn system, there are two main processes for consideration: the exchange interaction of magnetic ions with free carriers and spin-lattice relaxation which couples magnetic ion system to the lattice.Here we summarize briefly our results which have been published so far. Magneto-optical studies on (Zn,Mn)Se/(Zn,Be)Se and (Cd,Mn)Te/(Cd,Mg)Te quantum wells with a type-I band alignment have been performed. Free carriers in these structures were created either by means of photogeneration or by modulation doping. Structures with n-type and p-type modulation doping have been examined. Phenomena related to the spin-and energy transfer between systems of magnetic ions, free carriers and lattice were in the center of attention. Efficiency of coupling of these systems was examined by selective heating:

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