Structural, Optical, and Magneto-Optical Properties in Diluted Magnetic Semiconductors Cd0.63-yMn0.37CoyTe Single Crystals

Abstract

We investigated the magneto-optical properties of diluted magnetic semiconductor Cd0.63-yMn0.37CoyTe single crystals grown using a vertical Bridgman method. From the temperature dependence of the band-gap energy, the Varshni temperature parameter alpha was found to increase linearly with increasing Co concentration y while beta decreased with y. The Faraday rotation as a function of photon energy with various Co compositions for CdMnCoTe in the temperature range of 10 to 300 K was measured. The Verdet dispersion curves were enhanced near the fundamental band gap energy. The Verdet constant becomes larger since because the effect of the sp-d exchange interaction is enhanced as the temperature is lowered. At 10 K, the Verdet constants of the Faraday rotation for the samples with y = 0, 0.01, 0.02, and 0.04 were observed to be -0.94, -1.41, -1.69, and -2.11 deg/G cm at 610 nm, respectively. The Verdet constant showed a maximum for the sample with y = 0.04, and the value was approximately 2.3 times larger than that of the Cd0.63Mn0.37Te crystal. The Faraday rotation increased as Co content was increased, and the origin of the enhancement of the Faraday rotation in CdMnCoTe crystals could be explained in terms of the magnetization.