Ohno H
The author is with the Laboratory for Electronic Intelligent Systems, Research Institute of Electrical Communication, Tohoku University, Katahira 2-1-1, Sendai 980-8577, Japan. E-mail:
Science. 1998 Aug 14;281(5379):951-5. doi: 10.1126/science.281.5379.951.
REVIEW Semiconductor devices generally take advantage of the charge of electrons, whereas magnetic materials are used for recording information involving electron spin. To make use of both charge and spin of electrons in semiconductors, a high concentration of magnetic elements can be introduced in nonmagnetic III-V semiconductors currently in use for devices. Low solubility of magnetic elements was overcome by low-temperature nonequilibrium molecular beam epitaxial growth, and ferromagnetic (Ga,Mn)As was realized. Magnetotransport measurements revealed that the magnetic transition temperature can be as high as 110 kelvin. The origin of the ferromagnetic interaction is discussed. Multilayer heterostructures including resonant tunneling diodes (RTDs) have also successfully been fabricated. The magnetic coupling between two ferromagnetic (Ga,Mn)As films separated by a nonmagnetic layer indicated the critical role of the holes in the magnetic coupling. The magnetic coupling in all semiconductor ferromagnetic/nonmagnetic layered structures, together with the possibility of spin filtering in RTDs, shows the potential of the present material system for exploring new physics and for developing new functionality toward future electronics.
综述 半导体器件一般利用电子的电荷，而磁性材料则用于记录涉及电子自旋的信息。为了在半导体中同时利用电子的电荷和自旋，可以在目前用于器件的非磁性III-V族半导体中引入高浓度的磁性元素。通过低温非平衡分子束外延生长克服了磁性元素的低溶解度，并实现了铁磁性的（Ga，Mn）As。磁输运测量表明，磁转变温度可高达110开尔文。讨论了铁磁相互作用的起源。还成功制造了包括共振隧穿二极管（RTD）在内的多层异质结构。由非磁性层隔开的两个铁磁性（Ga，Mn）As薄膜之间的磁耦合表明空穴在磁耦合中起关键作用。所有半导体铁磁/非磁性层状结构中的磁耦合，以及RTD中自旋过滤的可能性，显示了当前材料系统在探索新物理和开发面向未来电子学的新功能方面的潜力。
