成型压力对CrO_2低温输运性质的影响  

Influence of the compacting pressure on the transport properties of CrO_2 at low temperatures

作　　者：聂颖[1] 隋郁[1] 宋秀丹[1] 王先杰[1] 程金光[1] 千正男[1] 苏文辉[1] 

机构地区：[1]哈尔滨工业大学物理系凝聚态科学与技术研究中心

出　　处：《物理学报》2006年第6期3038-3042,共5页Acta Physica Sinica

基　　金：国家自然科学基金项目(批准号:10304004)资助的课题~~

摘　　要：本文研究了压力对CrO2样品低温磁输运性质的影响.样品的X射线衍射结果表明(110)峰的相对强度随压力的增加而增大,说明压力对CrO2针状纳米颗粒有取向的作用.低温时CrO2样品的电阻和磁阻均随压力的增加而减少.实验结果表明,低温下样品的电导呈现出典型的晶粒间隧穿特征,其Δ值随着压力和磁场的增加而减小,并且Δ随磁场的变化幅度与成型压力有关,成型压力越高,Δ随磁场的变化越小.这些变化可以归因为压力对晶粒间隧穿势垒的调制.The influence of pressure on the magnetotransport properties of CrO2 samples at low temperatures has been studied in this paper. The X-ray diffraction patterns of the samples show that the relative intensity of （110） peak increases with increasing pressure, which implies that pressure has the orientation effect on the CrO2 needle-shaped nanoparticles. At low temperatures, the resistance and magnetoresistance of CrO2 samples decrease with the increase of pressure. The experimental results suggest that at low temperatures, the conductance of the sample shows the typical characteristic of intergranular tunneling. △ decreases with increasing pressure and magnetic field ; and furthermore, the range of change of △ with the magnetic field is relatied to the compacting pressure. The higher the compacting pressure, the smaller the variation of △ with the magnetic field. These changes can be attributed to the adjustment of pressure on the intergranular tunnel barrier.

关 键 词：磁阻 压力 隧穿 势垒厚度 

分 类 号：O513[理学—低温物理] TQ534.2[理学—物理]