Luminescence of Cd0.7Mn0.3Te crystals in transverse magnetic field

Photoluminescence of cleaved Cd0.7Mn0.3Te crystals is studied at T approximate to 1.6 K at the normal- and oblique (45 degrees) incidence of the pumping Ar laser beam (lambda = 488 nm) in magnetic fields -7 <= B <= 7 T in the Voigt geometry. At B = 0, photoluminescence maximum is found at 2.0819 eV at normal incidence (and backward emission) whereas the oblique incidence and emission shows photoluminescence maximum intensity at 2.0536 eV. The red shift of photoluminescence maximum position with the rise in B is observed and the results are found to be in good agreement with sp-d exchange interaction model for the oblique incidence case. Backward emitted photoluminescence line is found to narrow from 26.2 to 23.5 meV with the rise in B from 0 to 7 T. Alloy disorder contribution exhibits opposite trend to broaden, as is calculated on the basis of the matrix of the energy gap dependence on x and B. Therefore the observed photoluminescence line narrowing is assigned to the suppression of magnetic fluctuation in magnetic field. A linear size of magnetic fluctuation is estimated to be about 1/5 of the free exciton diameter. Photoluminescence maximum position difference in the normal- and oblique incidence cases is assigned to polaritons.