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利用水热法和旋涂工艺制备Co2+掺杂CdO基稀磁半导体纳米薄膜,研究样品的微观结构及电磁性能等。结果表明:样品是具有岩盐矿结构的CdO晶体结构,薄膜中粒子的平均粒径约20nm,且随Co摩尔(下同)掺量的增加而减小。样品中Co离子为正二价,属替位掺杂;样品呈现出明显的室温铁磁性,饱和磁矩随Co2+掺量的增加先增大后减小,在Co2+掺量为4.33%时达到最大值。样品的电导率随Co2+掺量的增加先减小后微弱增大,在Co2+掺量约为6%时达到最小值。磁电阻效应测量结果表明:样品呈现出室温的正磁电阻效应,磁电阻随Co2+掺量的增加先增大后减小,在Co2+掺量约为7%时达到最大值。利用Ruderman-Kittel-Kasuya-Yoshida(RKKY)机制、间接超交换机制和直接超交换机制等模型合理解释样品的铁磁性起源和磁电阻效应产生的物理机制。
Co2 + -doped CdO-based diluted magnetic semiconductor nanofilms were prepared by hydrothermal method and spin-coating method. The microstructure and electromagnetic properties of the samples were studied. The results show that the sample is a CdO crystal structure with rock salt mineral structure. The average particle diameter of the film is about 20 nm, and decreases with the increase of Co mole. The Co ions in the sample are positive divalent and belong to the substitutional doping. The samples show obvious room temperature ferromagnetism. The saturation magnetic moment firstly increases and then decreases with the increase of Co2 + content, reaching the maximum when the content of Co2 + is 4.33% . The conductivity of the sample decreases first and then increases slightly with the increase of Co2 + content, and reaches the minimum when the content of Co2 + is about 6%. The results of magnetoresistance show that the samples exhibit positive magnetoresistance effect at room temperature. The magnetoresistance first increases and then decreases with the increase of Co2 + content, reaching the maximum when the content of Co2 + is about 7%. The physical mechanism of the ferromagnetic origin and the magnetoresistance effect of the samples are reasonably explained by the models of Ruderman-Kittel-Kasuya-Yoshida (RKKY) mechanism, indirect super-exchange mechanism and direct super-exchange mechanism.