Zn0．97Cr0．03,O的PLD制备及其铁磁性

Ferromagnetism of Zn_(0.97)Cr_(0.03)O synthesized by PLD

采用脉冲激光沉积(PLD)的方法在石英基片上制备了不同氧分压(0,0.05,0.15和0.20 Pa)下Zn0.97Cr0.03O薄膜,并测量了它们的磁性、XRD谱、PL谱及XPS谱等.实验结果表明,所有的样品都具有良好的结晶性,且都沿c轴高度取向;磁测量结果表明,四个样品都具有铁磁性,且在氧压为0.15 Pa下沉积的薄膜磁性最强;四个样品都存在VZn,Oi,Zni,VZn,VO缺陷,尤其是VZn对应共振峰面积占所有缺陷总面积的百分比和样品的饱和磁化强度具有相同的变化趋势,表明Zn0.97Cr0.03O磁性与锌空位密切相关;四个样品中都存在Cr3+离子,且在0.15 Pa时Cr3+的含量最多.上述实验结果表明,Cr3+和VZn的缺陷复合体是ZnO:Cr样品具有稳定的铁磁有序的最有利条件,它证实了早先的基于第一性原理的计算结果.

Four Zn0.97Cro.030 films were deposited on quartz wafers in various oxygen environment （0, 0.05, 0.15 and 0.2 Pa） using pulsed laser deposition （PLD）. The films were characterized by XRD, PL, XPS, magnetic and electrical properties. Experimental results indicate that： （1） All the films are well crystallized and display a pure （002） orientation. （2） All the films have ferromagnetism, and the film deposited at 0.15 Pa has the biggest Ms. （3） There exist Vzn, Oi, Zni, Yz~ and Vo defects in the four films above, and the percentage of resonance peak area for Vzn to the total area of all defects as a function of oxygen pressure is similar to Ms, which means that the magnetizations of the samples are closely related to Zn vacancy Vzn. There is a Cr3＋ state in the four films when the content of Cr3＋ is the largest at 0.15 Pa. To sum up, the experimental results indicate that the substitutive Cr in the oxidation state of t3 and the neutral Zn vacancy in the Zn0.97Cr0.030 films is the most favorable defect complex to maintain a high stability of ferromagnetic order, which is consistent with the calculated results by the first-principle calculations.