稀土Dy、退火对Dy_x(Co_(40)Ag_(60))_(100-x)颗粒膜的结构与巨磁电阻效应的影响

Influence of Dy Content and Annealing Temperature on the Structure and Giant Magnetoresistance of Dy_x(Co_(40)Ag_(60))_(100-x) Granular Films

采用磁控溅射法制备了Dyx(Co40Ag60)100-x颗粒膜。X射线衍射实验结果表明,Dyx(Co40Ag60)100-x颗粒膜的晶体结构具有一定的择优取向,退火温度升高能够促进这种择优取向并加速Ag颗粒的聚集生长和Ag中的Co发生相分离;稀土元素Dy起到细化晶粒的作用,并且阻碍晶面择优取向的进程,导致薄膜结构中的晶界增多从而引起薄膜电阻变大。巨磁电阻(GMR)效应测量结果表明,对所有不同成分薄膜样品当退火温度高于250℃时,GMR值是趋于减小的。由于掺杂稀土元素Dy会引起薄膜电阻的增大从而导致GMR效应减小的趋势,但少量的Dy元素(x=0.7)和适当的退火处理即能保持GMR效应的稳定性又能提高它对磁场的灵敏度,GMR和S的最大值分别为-18%和1.5×10-4(A/m)-1。

Dyx（Co40Ag60）100-x（x=0,0.7,1.4,2.1,2.8,3.5） granular films was prepared by DC magneto controlled sputtering method.The XRD data indicated that Dyx（Co40Ag60）100-x films favors the（111） plane preferential orientation.The high annealing temperature can promote the（111） plane of Ag preferential orientation and Co dissolving in Ag to separate from Ag and accelerate grain growing.Dy element plays the role of a grain refiner and retards the（111） plane preferential orientation and result in increasing grains boundary and resistance of films.Magnetic measurements indicated that the values of GMR of all films decrease when annealing temperature is higher than 250 ℃ because of the increase of resistance of films,but it can enhance sensitivityof films doped small Dy element.For small amount of Dy to CoAg granular films and proper heat treatment,Dy element can keep the value of GMR a constant and enhance sensitivity.Both maximum value of GMR and its sensitivity are-18% and 1.5×10-4（A/m）-1,respectively.