Current-induced domain-wall switching in a ferromagnetic semiconductor structure
Current-induced domain-wall switching in a ferromagnetic semiconductor structure
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DOI：
10.1038/nature02441
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发表时间：
2004-04
期刊：
影响因子：
64.8
通讯作者：
M. Yamanouchi;D. Chiba;F. Matsukura;H. Ohno
中科院分区：
文献类型：
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作者：
M. Yamanouchi;D. Chiba;F. Matsukura;H. Ohno
磁信息存储依靠外部磁场通过磁化反转对逻辑位进行编码。但由于操作超密集存储设备所需的磁场太高而无法产生，电流磁化反转作为一种有前途的替代编码方法引起了人们的兴趣。事实上，自旋极化电流可以通过转矩改变纳米级金属结构的磁化方向。然而，目前所需的107-108A cm-2的高电流密度超过了集成电路金属互连所能容忍的阈值。在金属系统中编码磁性信息也可以通过操纵不同磁化方向区域边界处的畴壁，，，，，，，来实现，但这种方法同样需要大约107A cm-2的高电流密度。在这里，我们证明了在铁磁半导体结构中，在没有磁场的情况下，使用密度低于105A cm-2的电流脉冲可以通过畴壁开关诱导磁化反转。目前系统的低开关速度和低铁磁转变温度是不切实际的。但是，如果这些问题能够得到解决，通过降低电流密度的电脉冲进行磁反转可以为磁信息存储应用提供一条途径。
Magnetic information storage relies on external magnetic fields to encode logical bits through magnetization reversal. But because the magnetic fields needed to operate ultradense storage devices are too high to generate, magnetization reversal by electrical currents is attracting much interest as a promising alternative encoding method. Indeed, spin-polarized currents can reverse the magnetization direction of nanometre-sized metallic structures through torque,,,; however, the high current densities of 107–108A cm-2that are at present required exceed the threshold values tolerated by the metal interconnects of integrated circuits,. Encoding magnetic information in metallic systems has also been achieved by manipulating the domain walls at the boundary between regions with different magnetization directions,,,,,,, but the approach again requires high current densities of about 107A cm-2. Here we demonstrate that, in a ferromagnetic semiconductor structure, magnetization reversal through domain-wall switching can be induced in the absence of a magnetic field using current pulses with densities below 105A cm-2. The slow switching speed and low ferromagnetic transition temperature of our current system are impractical. But provided these problems can be addressed, magnetic reversal through electric pulses with reduced current densities could provide a route to magnetic information storage applications.