La2/3Ca1/3MnO3/Eu2CuO4/La2/3Ca1/3MnO3磁性隧道结的制备与表征

采用磁控溅射，紫外线光刻和离子束刻蚀制备了La_2/3Ca_1/3MnO₃/Eu₂CuO₄/La_2/3Ca_1/3MnO₃磁性隧道结.通过对获得的磁性隧道结的I-V特性测量，发现非线性的I-V特性，显示结样品的隧穿特性.有趣的是发现在电极材料La_2/3Ca_1/3MnO₃的金属-绝缘体转变温度(Tp)以下，I-V曲线出现一个跳变.随着温度降低，开始出现跳变的临界电流增大，但是跳变都发生在同样的电压下～209mV.当电流增大或减小在跳变点附近出现回滞.这一跳变只发生在铁磁金属态，表明这是一个磁性相关联的效应，可能对应一种新的磁性开关过程.虽然，目前对这一现象背后的物理机理还不清楚，但是，这一现象有可能在未来自旋电子学器件方面具有潜在的应用价值. 关键词： 庞磁电阻 磁性隧道结 开关效应

Fabrication and characterization of La2/3Ca1/3MnO3/Eu2CuO4/ La2/3Ca1/3MnO3 magnetic tunneling junctions

Magnetic tunneling junctions of La_2/3Ca_1/3MnO₃/Eu₂CuO₄/ La_2/3Ca_1/3MnO₃ have been fabricated by RF-magnetron sputtering, photolithography and ion beam etching. Tunneling effect was observed in these junctions by measuring their I-V curves. Interestingly, a discontinuity was observed in the I-V curves below the metal-insulator transition temperature (Tp) of La_2/3Ca_1/3MnO₃ By changing temperatures, the discontinuity in I-V curves happens at the same voltage of 209mV, but starts at different currents. The discontinuity starting current (Ic) decreases with increasing temperature. There is a hysteresis near the discontinuity when the current increases and decreases. The discontinuity in I-V curves could indicate a novel switching process. This switching phenomenon occurs only in the ferromagnetic metal state and strongly suggesting a magnetic related effect. The physics of the switching process has not been understood yet, but it could be of interest for potential applications in spintronic devices.