Ferroelectric and magnetic properties of CdMnS films prepared by coevaporation

We report on impurity ferroelectricity and ferromagnetic properties in semiconductor-structured CdMnS films. We observed ferroelectric hysteresis in CdMnS. A remnant polarization of 1.72 mu C/cm(2) and a coercive field of 14.3 kV/cm were obtained in samples with Mn concentration below 2%. The coevaporated CdMnS samples become ferromagnetic when doped with Au, with a spontaneous magnetization of 1.39x10(-6) emu and a coercive magnetic field of 75.4 gauss at 10 K, and the Curie point was found to be higher than room temperature. Through magnetic force microscopy, we observed clear magnetic clusters with sizes ranging from a few nanometers to 102 nm, and found the magnetization to be highly dependent on Au concentration. A combination of this ferroelectricity in CdMnS and ferromagnetism in Au-doped CdMnS may find use in ternary bit nonvolatile memory devices. (c) 2007 American Institute of Physics.