Mn spin domains in highly photoexcited (Cd,Mn)Te/(Cd,Mg)Te quantum wells

Direct spin and energy transfer between a dense two-dimensional electron-ho le (e-h) magnetoplasma and a Mn spin subsystem via spd exchange has been st udied. Time-resolved photoluminescence spectra of the magnetoplasma excited by a powerful 10-ns laser pulse in a single Cd0.97Mn0.03Te/Cd0.75Mg0.25Te quantum well have been investigated in magnetic fields B less than or equal to 14 T at helium temperature. A giant asymmetry of the plasma spin splitt ing has been observed in the spectra of dense homogeneously photoexcited pl asma at high magnetic fields. This asymmetry has been explained in terms of formation of a domain structure within the magnetic subsystem, i.e., spati al stratification into regions with different Mn-spin temperatures. The Mn spin domains result from the Mn spin heating due to the direct spin-spin sd exchange between hot carriers and Mn via effective spin-hip scattering of electrons with simultaneous spin-flip of Mn. During the Mn spin heating und er quasistationary excitation, first the Mn spin fluctuations grow and spin domains form, then the spin domain's volume increases. The spin domain's f ormation occurs due to resonant spin-flip scattering with a characteristic time similar to 1 ns. The nonresonant Mn spin heating has been observed als o with a characteristic time of similar or equal to 10 ns. [S0163-1829(98)0 9039-0].