Enhancement of the magneto-optical effect by the addition of Co to pseudo-quaternary II–VI magnetic semiconductor CdMnCoTe films

Abstract

The magneto-optical properties of pseudo-quaternary magnetic semiconductor CdMnCoTe films deposited on quartz glass substrates by using molecular beam epitaxy (MBE) equipment were studied in the visible wavelength region at room temperature. The deposition was carried out at an average rate of ∼1 A/sec for 8 h by using a 4-N Co target sputtered by an electron gun with an emission current of 20 mA, a 5-N CdTe effusion cell heated to 490 °C, and a 4-N MnTe cell heated at 1020 °C. Using this system, we prepared ∼2-µm-thick CdMnTe and CdMnCoTe films on 0.5-mm-thick quartz glass substrates. These films exhibited a preferred (111) growth and paramagnetic characteristics. The magnetization intensities at 15 kOe and room temperature of the two films were similar; approximately 2.5 × 10−4 emu for the Cd0.65Mn0.35Te film and 2.8 × 10−4 emu for the Cd0.56Mn0.39Co0.05Te film. The Faraday rotation measured at 620 nm in the CdMnCoTe film was −0.32 deg/cm-G, and that in the CdMnTe film was −0.10 deg/cm-G. The Faraday rotation was significantly enhanced in the CdMnCoTe films. Direct ac Faraday rotation observations of the films were successfully performed under 1.27-kHz ac fields generated by using a ring magnet.