Magneto-optical properties for bulk Cd0.63−yMn0.37HgyTe single crystals

Abstract

We investigated the magneto-optical properties of diluted magnetic semiconductor Cd1−x−yMnxHgyTe (x∼0.37) single crystals grown using a vertical Bridgman method. This material crystallizes in the zinc-blende structure for values of y⩽0.07. The band gap energy increases with increasing y (⩽0.03), while decreases with increasing y (⩾0.03). An anomalous behavior was also observed in the magnetic susceptibility and electrical resistivity. Faraday rotation as a function of photon energy with various Hg compositions for CdMnHgTe in the temperature range of 10–300K has been measured. The Verdet dispersion curves were enhanced near the fundamental band gap energy. The Verdet constant becomes larger since the effect of the sp-d exchange interaction is enhanced as the temperature is lowered. At 10K, the Verdet constants of the Faraday rotation for the samples with y=0, 0.01, 0.03, 0.05, and 0.07 were observed to be −1.09, −2.57, −3.94, −0.97, and −0.87deg∕Gcm at 613nm, respectively. The Verdet constant showed a maximum for the sample with y=0.03, and the value is approximately four times larger than that of the Cd0.63Mn0.37Te crystal. The Verdet constant has a maximum around Hg compositions with y∼0.03, and this result agrees well with the behavior of the magnetic susceptibility. This result reflects that Hg ion mediates and enhances the spin-spin interaction between Mn2+ ions with increasing Hg composition up to y∼0.03.