退火处理对Dy4(Co21Cu79)96颗粒膜结构和巨磁电阻效应的影响

摘要

Dy4 (Co21Cu79)96 granular films were prepared by a DC magnetron sputtering method. The giant magnetoresistance (GMR) and magnetic properties of the films were studied. XRD was used to examine the composition and structure of granular films. The GMR of the films was measured by the four-point method. Vibration sample magnetometer was used to measure the magnetic properties. The XRD data indicate that the as-deposited films form a single phase metastable fee alloy structure. Annealing can promote Co dissolving in Cu to separate from Cu. GMR measurements indicate that GMR values ofrnall films increase at first and then decrease with the increaseing annealing temperature. The maximumrnGMR value of -4. 68% was obtained for Dy4 (Co21Cu79)96 thin film after annealing at 425 ℃ for 30 min.rnHysteresis loops of the as-deposited and annealed samples indicate the change from superparamagnetic tornferromagnetic contribution to the GMR effect. The value of coercivity (Hc) increases with annealingrntemperature.%采用磁控溅射法制备Dy4 (Co21 Cu79)96颗粒膜,研究薄膜的巨磁电阻(GMR)效应及磁性能.应用X射线衍射仪(XRD)对薄膜微观结构随退火温度的变化进行分析,采用四探针及振动样品磁强计(VSM)测量薄膜的磁电阻和磁性能.X射线衍射实验结果表明:制备态的薄膜形成了单相亚稳态面心合金结构,退火处理将促进Cu和Co的相分离.磁电阻测试发现:所有不同成分的Dyx (Co21 Cu79)100-x(x=0,4,8,9,12,14)薄膜样品均随着退火温度的升高,颗粒膜巨磁电阻(GMR)效应不断增大,当达到最佳退火温度之后,GMR值又随退火温度的升高而降低.当退火温度为425℃时,Dy4 (Co21 Cu79)96薄膜的巨磁电阻效应达到最大,GMR值为-4.68％.退火前后样品磁滞回线的变化表明薄膜中发生了从超顺磁性到铁磁性的转变,矫顽力Hc随退火温度的升高逐渐增大.