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

采用光刻技术制备了由不耦合磁性多层材料组成的微结构磁电子器件。基于自旋相关电子输运的基本器件性能已经得到了研究。微结构多层结构中的敏感自旋阀效应。通过直接电子束光刻和氩离子研磨，制备了宽度为0.4 μ m的Ni-Fe/Cu/Co多层微结构条带图，在20 μ e的外场下获得了6%的高灵敏度磁电阻（MR）变化。电流垂直于平面（CPP） ME器件的制造。——开发了三维电极CPP-ME器件的微加工工艺。在室温下，对Co/Cu/CuO/Co的铁磁隧道结进行了8momega的磁流变，并通过原位射频等离子体氧化形成了隧道势垒CuO。在非磁性层为a-Si或a-Ge的CPP-ME器件中也观察到MR效应，这表明非晶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。——设计并制备了横向尺寸为2*5 μ m^2的蒸发Ni-Fe/Co/Cu/Co组成的M-RAM存储单元。以20 ns脉冲宽度的导体电流进行高速双稳态比特状态变化（写入操作），并通过磁流变测量（读取操作）进行电检测。

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).