Orthorhombic symmetry of valence-band states in CdTe/Cd1−x MnxTe quantum wells

A study is reported of the anisotropy in magnetic-field-induced linear polarization in (001) CdTe/Cd_1−x Mn_xTe quantum wells. The observed limiting anisotropy is shown to be due to the low C _2v symmetry of the quantum well. The relations obtained for the C _2v point group are in a good agreement with experiment. Considered on the microscopic scale, the effect is associated with the heavy-hole g-factor anisotropy in the well plane. Fiz. Tverd. Tela (St. Petersburg) 41, 903–906 (May 1999)     

Trions in quantum-well structures with two-dimensional electron gas

A study has been made of bound exciton-electron complexes (trions) and unbound exciton-electron states (combined exciton-cyclotron resonance) from reflectance spectra obtained from modulation-doped CdTe/CdMgTe quantum-well structures. It has been established that the contribution of trions to dielectric permittivity is comparable to that of excitons. An analysis is made of the magnetic-field dependence of the parameters describing the contribution to dielectric permittivity due to exciton-cyclotron-resonance states. Fiz. Tverd. Tela (St. Petersburg) 40, 813–815 (May 1998)     

On the quantum limit behaviour of the magnetoresistance in non-parabolic semiconductors

The quantum limit behaviour of the magnetoresistance in narrow-gap semiconductors is investigated. The non-parabolicity of the energy dispersion is taken into account in the density of states. Assuming constant level broadening, both the longitudinal and the transverse magnetoresistance obey asymptotic power laws. The exponents in these power laws are found to be larger than in the case of parabolic energy dispersion.     

Spin and orbital quantization of electronic states as origins of second harmonic generation in semiconductors

Basically different mechanisms of optical second harmonic generation (SHG) in semiconductors, induced by an external magnetic field H, have been identified experimentally by studying the diluted magnetic semiconductor (Cd,Mn)Te. For paramagnetic (Cd,Mn)Te the SHG response is governed by spin quantization of electronic states, in contrast with diamagnetic CdTe with its dominating orbital quantization. The mechanisms can be identified by the distinct magnetic field dependence of the SHG intensity which scales with the spin splitting in the paramagnetic case as compared to the H2 dependence observed for the diamagnetic case.     

Influence of nonequilibrium phonons on exciton luminescence in CdTe/CdMnTe quantum wells

The luminescence method has been employed for the first time to detect nonequilibrium phonons in CdTe quantum wells with Cd_0.6Mn_0.4Te barriers. The method makes use of the giant Zeeman splitting of exciton states in CdTe/(Cd,Mn)Te quantum wells and is promising for application in high-sensitivity subterahertz phonon spectrometry. The method can also be useful in revealing the spin-phonon coupling mechanisms in diluted magnetic semiconductors. Fiz. Tverd. Tela (St. Petersburg) 40, 816–819 (May 1998)     

Magnetic origin of the temperature variation of the band offsets in the CdTe/(Cd,Mn)Te heterostructures

Il Nuovo Cimento D - Precise-temperature-dependent measurements of energy of excitons confined in CdTe/CdMnTe quantum wells and superlattices were performed between 2 K and 100 K. We show that...     

The longitudinal magnetophonon effect in semiconductors containing magnetic impurities

The dependence of longitudinal magnetoresistance on magnetic field in semiconductors containing magnetic impurities is investigated theoretically. The calculation takes into account the scattering of electrons on magnetic impurities and on optical phonons. The inelastic optical phonon scattering itself is responsible for magnetophonon oscillations of the magnetoresistance, the extremes of these oscillations occuring when energy distance between Landau levels is equal to the energy of optical phonon, $\text{h}\text{?}$ω₀. The scattering on magnetic impurities may lead to spin flip electronic transitions. The spin flip electronic transitions manifest themselves as additional minima on the oscillatory picture of magnetoresistance. These new minima occur when the energy separation between spin-split Landau levels is equal to $\text{h}\text{?}$ω₀.