L. C. Smith

Exciton polaritons in quantum wells in a transverse magnetic field

This paper reports on a study of the exciton polariton region in reflection spectra of wide CdTe/CdZnTe quantum wells (with well width exceeding by far the exciton Bohr radius) measured in Voigt geometry in a magnetic field. In a magnetic field, forbidden exciton lines were observed to appear for each exciton quantization level. The exciton diamagnetic shift constant has been observed to decrease noticeably with increasing number of the quantum confined level. A comparison of calculated with experimental spectra reveals a growth of the exciton translational mass with increasing magnetic field. It has been shown that both the growth of mass and the decrease of the diamagnetic shift can be traced to mixing of exciton internal with translational motion states.

Electron paramagnetic resonance of manganese ions in CdTe detected by coherent Raman spectroscopy

Electron paramagnetic resonance (EPR) signals of manganese ions in cadmium telluride have been detected optically by a coherent Raman heterodyne method. This technique circumvents the resolution limits of diffraction grating-based spectroscopy while providing the sensitivity and selectivity characteristic of resonant Raman scattering. The precision to which the spin Hamiltonian parameters of a given center can be determined is greatly enhanced and, here, the effects of the hyperfine interaction between the Mn2+3d electrons and the Mn nucleus on the line shape of the spectrum become apparent. The Raman scattering process is found to be strongly resonant with an excitonic intermediate state, due to the strong exchange coupling between band and Mn 3d states. This opens the way to optically site-selective EPR measurements of the symmetry, charge state and exchange interactions of transition metal ions in semiconductor quantum wells and dots.