Spintoronics Devices using Transport Properties

在半导体/金属混合结构中观察到的磁阻开关效应被认为是在磁场作用下其非线性电流-电压特性恢复到线性的效应。为了阐明磁阻开关效应的起源，从2002财年到2003财年，我们研究了磁阻开关效应的必要结构条件，并成功地观察到了在GaAs衬底上制作的Au带隙结构的磁阻开关效应。2004财年，我们在Au带隙结构中发现了电致发光现象。此外，空间分辨电致发光测量表明，非线性输运不是在Au电极之间的GaAs面上进行的，而是在GaAsAu/Au的异质界面上进行的。这一结果表明了这种效应在器件应用方面的优势，因为与表面相比，界面更稳定，更容易操作。在2005财年的后半期，我们深入研究了界面与磁阻开关效应之间的关系，最终得出结论：具有结构无序的异质界面样品表现出非线性输运，而不是与磁场有关。也就是说，实验结果证明金属/半导体界面是发生磁阻开关效应的场所。

Magnetoresistive switch effect observed in a semiconductor / metal hybrid structure is considered to be an effect in which its non-linear current-voltage characteristics recover to the linearity under the magnetic field. In order to elucidate the origin, from FY2002 to FY2003, we investigated the necessary structural conditions for the magnetoresistive switch effect, and succeeded in observing the effect in a Au gap structure fabricated on a GaAs substrate. In FY2004, we found the electro-luminescence phenomena in the Au gap structure. Furthermore, the space-resolved electro-luminescence measurements showed that the non-linear transport was thought to progress not on the GaAs surface between the Au electrodes, but at the heterointerface between GaAs and Au. This result indicates the advantage in terms of the device application using this effect, because the interface is much stable and easiertrrbe-liandled comparing to the surface. In the last half period of FY2005, we intensively investigated the relationship between the interface and the magnetoresistive switch effect, then finally, we achieved the conclusion that the sample with the structurally disordered heterointerface shows the non-linear transport, but not the magnetic field dependence. Namely, the experimental results proved that the metal / semiconductor interface is the arena where the magnetoresistive switch effect takes place.