Microstructured Magnetcoelectronic Devices Based on Spin Dependent Electron Scattering with Magnetic Multilayrs

采用光刻技术制备了由非耦合磁性多层膜构成的微结构磁电子器件。基于自旋相关的电子输运，研究了基本器件的性能。微结构多层膜中敏感的自旋阀效应。-在Ni-Fe/Cu/Co微结构条形图案和电子束蒸发沉积的基多层膜中，在20 Oe的外场下获得了6%的高灵敏磁阻(MR)变化。通过对不同图案宽度到0.4微米的条形图案的MR测量，阐明了静磁形状的影响，这些条形图案是用直接电子束光刻和Ar离子研磨构成的。垂直于平面(CPP)微电子器件的制作。-开发了三维电极CPP-ME器件的微加工工艺。采用射频等离子体原位氧化技术制备了Co/Cu/CuO/Co铁磁隧道结，在室温下观察到了8mOMEGA的MR变化。在以a-Si或a-Ge为非磁层的CPP-ME器件中也观察到了MR效应，这表明非晶态半导体中的电子输运依赖于自旋。磁随机存取存储器(M-RAM)的发展-设计并制作了一种M-RAM存储单元，该存储单元由横向尺寸为2*5微米的蒸发Ni-Fe/Co/Cu/Co和覆盖的导体图案组成。利用20 ns脉冲宽度的导体电流进行高速双稳位状态改变(写入操作)，并通过MR测量进行电检测(读取操作)。

Microstructured magnetoelectronic (ME) devices, composed of uncoupled magnetic multilayrs, have been fabricated with lithographic techniques. Fundamental device performance, based on the spin dependent electron transport, have been studied.1. Sensitive spin valve effect in microstructured multilayrs. --- Highly sensitive magnetoresistance (MR) change of 6% for the external field of 20 Oe was attained in a microstructured strip pattern of Ni-Fe/Cu/Co and based multilayr, deposited with an electron beam evaporation Magnetostatic shape effects were clarified from the MR measurements of strip patterns with various pattern widths down to 0.4 mum, which were structured with a direct electron beam lithography and Ar ion milling.2. Fabrication of corrent perpendicular to plane (CPP) ME devices. --- Microfabrication processes for CPP-ME devices with three dimentional electrodes been developed. MR change of 8 mOMEGA was observed at room temperature for a ferromagnetic tunnel junction of Co/Cu/CuO/Co, which tunnel barrier CuO was formed with in-situ rf plasma oxidation. MR effects were also observed in CPP-ME devices with a-Si or a-Ge as nonmagnetic layrs, which suggest the spin dependent electron transport in amorphous semiconductors.3. Development of magnetic random access memory (M-RAM). ---A M-RAM memory cell composed of evaporated Ni-Fe/Co/Cu/Co with lateral size of 2*5 mum^2 and an overlaid conductor pattern was designed and fabricated. High speed bistable bit state change (write operation) was performed with conductor current of 20 ns pulse width, and electrically detected by MR measurement (read operation).