Electric-field-driven switching of individual magnetic skyrrnions
Electric-field-driven switching of individual magnetic skyrrnions
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DOI：
10.1038/nnano.2016.234
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发表时间：
2017-02-01
影响因子：
38.3
通讯作者：
Wiesendanger, Roland
中科院分区：
文献类型：
--
作者：
Hsu, Pin-Jui;Kubetzka, Andre;Wiesendanger, Roland
用电场控制磁性是开发未来节能设备的关键挑战（1，2）。目前的磁信息技术主要基于需要局部磁场或自旋力矩的写入过程，但也已经证明，在施加电场时可以改变磁特性（2-5）。这归因于由自旋相关屏蔽和能带结构的修改（6-8）、原子位置的变化（5，9，10）或与相邻氧化物层的杂化差异（4，11）引起的磁晶各向异性的变化。然而，在与时间反转相关的状态之间的切换（例如，如本技术中所使用的上下磁化）并不简单，因为电场不破坏时间反转对称性。已经应用了几种解决方法来在具有电场的磁性状态之间切换（12，13），包括由于电场而导致的材料成分的变化（14）。在这里，我们证明了局部电场可以用来在磁skyrmion（15，16）和铁磁状态之间可逆地切换。这两个状态在拓扑上是不等价的，我们发现电场的方向直接决定了最终的状态。这一观察建立了将联合收割机电场写入与最近设想的Skyrmion跑道型存储器相结合的可能性（17，18）。
Controlling magnetism with electric fields is a key challenge to develop future energy-efficient devices(1,2). The present magnetic information technology is mainly based on writing processes requiring either local magnetic fields or spin torques, but it has also been demonstrated that magnetic properties can be altered on the application of electric fields(2-5). This has been ascribed to changes in magnetocrystalline anisotropy caused by spin-dependent screening and modifications of the band structure(6-8), changes in atom positions(5,9,10) or differences in hybridization with an adjacent oxide layer(4,11). However, the switching between states related by time reversal, for example magnetization up and down as used in the present technology, is not straightforward because the electric field does not break time-reversal symmetry. Several workarounds have been applied to toggle between bistable magnetic states with electric fields(12,13), including changes of material composition as a result of electric fields(14). Here we demonstrate that local electric fields can be used to switch reversibly between a magnetic skyrmion(15,16) and the ferromagnetic state. These two states are topologically inequivalent, and we find that the direction of the electric field directly determines the final state. This observation establishes the possibility to combine electric-field writing with the recently envisaged skyrmion racetrack-type memories(17,18).