Resonant coherent Raman spectroscopy on short-period CdTe/MnTe superlattices

Short-period (CdTe)(m)/(MnTe)(n) superlattices were investigated by means of coherent Raman scattering (CRS) in backscattering geometry in the temperature range between 1.7 K and well above the Neel temperature of MnTe (about 70 K). Magnetic fields up to 7 T were applied in Voigt configuration. The method allows the observation of spin splittings of delocalized band carriers as well as of electrons localized on magnetic ions. There are two types of resonances which we attribute to intra-Mn 3d transitions. One of them shows features characteristic for a paramagnetic resonance (PMR), the other one behaves like a Raman antiferromagnetic resonance (AFR). However, in contrast to usual paramagnetic resonances observed in diluted magnetic CdMnTe, the oscillator strength of PMR decreases with increasing temperature. Due to the exchange interaction with Mn ions close to the CdTe/MnTe interfaces the free-electron spin resonance exhibits a splitting larger than expected for electrons confined in CdTe wells. In a sample with only 5 monolayers of CdTe the free-carrier spin resonance behaves qualitatively similar to bound magnetic polarons in doped CdMnTe alloys. (C) 1998 Elsevier Science B.V. All rights reserved.