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arXiv 0904.4807cond-mat.mtrl-sci
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Zn1-x Co(x)O薄膜的结构、光学、磁学和电学性质

Structural, optical, magnetic and electrical properties of Zn1-x Co (x) O thin films

M. Tay, Y. H. Wu, G. C. Han, Y. B. Chen, X. P. Pan, S. J. Wang, P. Yang, Y. P. Feng

摘要:

尽管人们对ZnO基磁性半导体的铁磁性进行了大量的研究,但其起源仍然存在争议。虽然在文献中经常报道用磁强计测量观察到室温以上的铁磁性,但迄今为止还没有用磁、光、电测量观察到相关铁磁性的报道。本文系统地研究了溅射法制备的Zn_(1-x)Co(x)O:Al薄膜(x = 0 ~ 0.33)的结构、光学、磁学和电学性质。我们表明,相关的铁磁性只存在于x > 0.25的样品。相比之下,x < 0.2的样品仅在磁学测量中表现出弱铁磁性,而在光学和电学测量中不存在。我们通过系统的电输运研究证明,对于x < 0.2的样品,载流子局域化确实发生在20-50 K以下;然而,这不会导致这些样品中形成铁磁相,电子浓度在6 x 10(19)cm(-3)1 x 10(20)cm(-3)范围内。详细的结构和光学透射光谱分析表明,在x > 0.25的样品中观察到的异常霍尔效应是由于第二相和Co团簇的形成。

英文摘要:

Despite a considerable effort aiming at elucidating the nature of ferromagnetism in ZnO-based magnetic semiconductor, its origin still remains debatable. Although the observation of above room temperature ferromagnetism has been reported frequently in the literature by magnetometry measurement, so far there has been no report on correlated ferromagnetism in magnetic, optical and electrical measurements. In this paper, we investigate systematically the structural, optical, magnetic and electrical properties of Zn1-x Co (x) O:Al thin films prepared by sputtering with x ranging from 0 to 0.33. We show that correlated ferromagnetism is present only in samples with x > 0.25. In contrast, samples with x < 0.2 exhibit weak ferromagnetism only in magnetometry measurement which is absent in optical and electrical measurements. We demonstrate, by systematic electrical transport studies that carrier localization indeed occurs below 20-50 K for samples with x < 0.2; however, this does not lead to the formation of ferromagnetic phase in these samples with an electron concentration in the range of 6 x 10(19) cm(-3) 1 x 10(20) cm(-3). Detailed structural and optical transmission spectroscopy analyses revealed that the anomalous Hall effect observed in samples with x > 0.25 is due to the formation of secondary phases and Co clusters.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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