成型压力对CrO2低温输运性质的影响

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. 关键词： 磁阻 压力 隧穿 势垒厚度

Influence of the compacting pressure on the transport properties of CrO2 at low temperatures

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. Δ decreases with increasing pressure and magnetic field; and furthermore, the range of change of Δ with the magnetic field is relatied to the compacting pressure. The higher the compacting pressure, the smaller the variation of Δ with the magnetic field. These changes can be attributed to the adjustment of pressure on the intergranular tunnel barrier.