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

利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。基于自旋相关电子输运的基本器件性能进行了研究.微结构多层膜中的灵敏自旋阀效应。- 在电子束蒸发沉积的Ni-Fe/Cu/Co和基于多层的微结构条带图案中，在20 Oe的外场下获得了6%的高灵敏磁阻（MR）变化。从具有各种图案宽度的条带图案的MR测量中澄清了静磁形状效应，所述图案宽度低至0.4 μ m，采用直接电子束光刻和氩离子铣削技术制作.电流垂直于平面（CPP）ME器件的制造。- 开发了具有三维电极的CPP-ME器件的微细加工工艺。用射频等离子体原位氧化法制备了Co/Cu/CuO/Co铁磁隧道结，在室温下观察到8 mOMEGA的磁电阻变化。在以a-Si或a-Ge为外延层的CPP-ME器件中也观察到了磁电阻效应，表明非晶外延层中存在自旋相关的电子输运.磁性随机存取存储器（M-RAM）的发展。- 设计并制造了由横向尺寸为2*5 mum^2的蒸发Ni-Fe/Co/Cu/Co和覆盖的导体图案组成的M-RAM存储单元。用20 ns脉冲宽度的导体电流进行高速的位状态变化（写操作），并通过MR测量进行电检测（读操作）。

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).