Magnetism of Co-doped ZnO thin films
Magnetism of Co-doped ZnO thin films
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DOI：
10.1103/physrevb.75.205206
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发表时间：
2007-05-01
影响因子：
3.7
通讯作者：
Goering, Eberhard
中科院分区：
文献类型：
--
作者：
Gacic, Milan;Jakob, Gerhard;Goering, Eberhard
研究了用脉冲激光沉积法在r面Al_2O_3衬底上制备的5%Co掺杂和未掺杂ZnO薄膜的磁性和输运性质。Co掺杂的薄膜表现出顺磁性和铁磁性，以及高的磁电阻和小的反常霍尔效应。在0 ~ 5 T的低温范围内，我们观察到磁阻的双符号变化。对于未掺杂的ZnO薄膜，由相同的条件下制备的，只有一个负MR观察到，但令人惊讶的是，也是一个非常小的异常霍尔效应。我们解释我们的结果，通过应用半经验拟合组成的积极和消极的贡献的磁阻。利用X射线磁性圆二色性研究了激光烧蚀ZnO薄膜中Co掺杂元素的比磁矩。由于Co原子表现出顺磁行为，我们将铁磁性归因于由于过渡金属掺杂和/或衬底界面应力引起的氧空位和缺陷引起的自发自旋杂质带。
We have investigated magnetic and transport properties of 5% Co-doped and undoped ZnO thin films deposited on r plane Al2O3 substrates by pulsed laser deposition. The Co doped films showed paramagnetic and ferromagnetic behavior as well as a high magnetoresistance and a small anomalous Hall effect. In a range of 0 to 5 T at low temperatures we observed a double sign change of the magnetoresistance. For undoped ZnO films, prepared by the same conditions, only a negative MR was observed, but surprisingly also a very small anomalous Hall effect. We explain our results by applying a semiempirical fit consisting of a positive and a negative contribution to the magnetoresistance. Using x-ray magnetic circular dichroism we investigated element specific magnetic moments in Co-doped laser ablated ZnO films. As the Co atoms show a paramagnetic behavior, we attribute the ferromagnetism to a spontaneously spin impurity band induced by oxygen vacancies and defects due to the transition metal doping and/or interface stress to the substrate.