Pressure Effects on Magneto-Optical Properties in Cadmium Telluride/(Cadmium, Manganese) Telluride Single Quantum Well with High Manganese Concentration

The pressure effect on the magnetic field induced type I-type II transition is studied in a CdTe/Cd<sub>1-x</sub>Mn<sub>x</sub>Te (x=0.24) single quantum well (SQW). Photoluminescence (PL) measurements under hydrostatic pressures up to 1.07 GPa and long pulsed magnetic fields up to 60 T with a pulse duration of 2 sec are reported. The pressures were generated in a plastic diamond anvil cell (DAC). A bend toward lower energies (additional red shift) is observed above 28.5 T in magnetic field dependence of the exciton energy for a 13 Aring thick quantum well. We attribute this red shift to a phenomenon preceding the type I-type II transition after a comparison with a simple quantum mechanical calculation. The onset field of the additional red shift increases by 3.4 T by applying a pressure of 1.07 GPa. Spin-spin coupling between the exciton and the Mn ion in the interface region is also investigated and found to be enhanced by pressure

INFRARED STUDY OF VIBRATIONAL PROPERTY AND POLYMERIZATION OF C-60 AND C-70 UNDER PRESSURE

Infrared spectra were measured for solid C60 and C70 to 7 GPa under hydrostatic or quasi-hydrostatic pressure at room temperature. Some vibrational modes showed negative or insensitive dependence of frequency on pressure, suggesting destabilization of C60 and C70 molecules by compression. In solid C60 new absorption bands gradually grew with increasing pressure in association with an intensity decrease of the original bands. These spectral changes were interpreted in terms of polymerization of C60 molecules. Polymerized molecules recovered at ambient pressure were converted back to the monomer by thermal annealing at 473 K