Study of ferromagnetic multiple-tunnel-junction devices

研究了基于利用自旋相关共振隧穿现象概念的新型器件。分析了两个量子威尔斯阱均由铁磁金属构成的铁磁三势垒结构的共振隧穿磁随机存储器（MRAM）的器件特性。计算表明，由铁磁三势垒结构组成的共振隧穿存储器可以提供10^4%量级的“1”和“0”的极高阅读电流比。这种特性对于非易失性超高密度自旋存储器是非常有前途的。此外，我们提出并分析了一种共振隧穿自旋滤波器，这是新兴的自旋电子学的关键器件之一，由铁磁GaMnAs基量子阱（QW）和非磁性GaAs QW组成。详细的计算表明，它可以产生高自旋极化电流，极化率超过98%。

Novel devices based on the concept of utilizing spin dependent resonant tunneling phenomena were investigated. The device characteristics of a resonant tunneling magnetic random access memory (MRAM) using a ferromagnetic triple-barrier structure in which both of two quantum wells are composed of ferromagnetic metals were analyzed. Calculations showed that the resonant tunneling memory consisting of a ferromagnetic triple-barrier structure could provide an exceedingly high reading current ratio for "1" and "0" of an order of 10^4%. This property is highly promising for nonvolatile ultrahigh-density spin-memory. Furthermore, we proposed and analysed a resonant tunneling spin filter, which is one of key devices for emerging spintronics, consisting of a ferromagnetic GaMnAs-based quantum well (QW) and a non-magnetic GaAs QW. Detailed calculations showed that it could produce high spin-polarized currents with polarizations exceeding 98 %.