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ABSTRACT Cr substituted dilute magnetic semiconductor Cd .,Cr,Se films were grown onto fused silica and sapphire (00 - 1) substrates by vapor deposition technique. The films with wurtzite structure were obtained at composition of 0• x • 0.66. Saturation magnetization and magnetic susceptibility increased as x increased. In comparison with Mn-DMS system, the initial magnetization curves saturate easily. This tendency is different from most DMS materials in which magnetic ions interact with each other antiferromagnetically. It is possible that ferromagnetic interactions exist in Cd,.xCrSe. INTRODUCTION Diluted magnetic semiconductors ( DMS ) exhibit novel magneto-optical phenomena such as a Faraday effect or a Zeeman splitting of electronic (band and impurity) levels. They arise from exchange interactions between magnetic ions and conduction- or valence- band electrons (sp-d exchange interaction) [1]. Since the first report in the end of 1970's [21, many studies have been done especially on the Mn-based DMS family. With developments in the crystal

growth of thin film by MBE etc., interest is recently attracted to quantum effects in superlattices [3]. The magneto-optical effects of DMS have also attracted much attention for their application to optoelectric materials. Onodera et. al. first practically applied Cd,.xMn•Te to optical isolators [4]. In most DMS families such as Cd1 xTxTe or Cd 1. TSe (T : Mn, Fe, Co), the exchange interaction between valence band p-type electrons and d-electrons of magnetic ions is antiferromagnetic, which leads to antiferromagnetic d-d interactions. As the concentration of magnetic ion increases, higher external magnetic fields are required to saturate the magnetization. Recently, the ferromagnetic phase was first discovered in III-V based DMSs, Ga, ,Mn•As and In-.,Mn.As [5]. For I1-VI based DMS systems, Cr substituted DMSs have been expected, sincep-d interactions in Zn,.•Cr•Se are ferromagnetic [6]. The d4 electronic configuration of the Cr ion makes both spin-down and spin-up electrons from the valance band jump onto the d-level, which is attributed to ferromagnetic p-d coupling. However, reports are limited to those about specimens with low concentrations (x'0 XRD patterns of Cd1 xCrxSe films of U 2000 x=0 and 0. 15 deposited on fused silica at the substrate temperature of 10005 . 300 'C . The strongest line is 0 80 100 60 20 40 assigned to be 00 - 2 reflection of the wurtzite structure. According to 2E) (deg.) powder XRD patterns of CdSe, the Fig. I X-ray diffraction patterns of Cd,-,CrSe films with x=0 and 0.15 deposited on fused silica at 3001C. The strongest line is the 10 - 0 reflection preferential orientation to the c-axis is seen. and second is the 11 - 0 reflection. The XRD patterns show the preferential orientation along the c-axis in the deposited films. The preferential orientation along the c-axis is also recognized for the deposited film on sapphire substrates. Fig. 2 shows XRD patterns of Cdl.,CrSe on sapphire (00 - 1), (11 • 0) and (01 - 2) substrates. No diffraction