利用拓扑表面态进行磁化切换。
Magnetization switching using topological surface states.
作者信息
Li Peng, Kally James, Zhang Steven S-L, Pillsbury Timothy, Ding Jinjun, Csaba Gyorgy, Ding Junjia, Jiang J S, Liu Yunzhi, Sinclair Robert, Bi Chong, DeMann August, Rimal Gaurab, Zhang Wei, Field Stuart B, Tang Jinke, Wang Weigang, Heinonen Olle G, Novosad Valentine, Hoffmann Axel, Samarth Nitin, Wu Mingzhong
机构信息
Department of Physics, Colorado State University, Fort Collins, CO 80523, USA.
Department of Physics, Pennsylvania State University, University Park, PA 16802, USA.
出版信息
Sci Adv. 2019 Aug 30;5(8):eaaw3415. doi: 10.1126/sciadv.aaw3415. eCollection 2019 Aug.
Topological surface states (TSSs) in a topological insulator are expected to be able to produce a spin-orbit torque that can switch a neighboring ferromagnet. This effect may be absent if the ferromagnet is conductive because it can completely suppress the TSSs, but it should be present if the ferromagnet is insulating. This study reports TSS-induced switching in a bilayer consisting of a topological insulator BiSe and an insulating ferromagnet BaFeO. A charge current in BiSe can switch the magnetization in BaFeO up and down. When the magnetization is switched by a field, a current in BiSe can reduce the switching field by ~4000 Oe. The switching efficiency at 3 K is 300 times higher than at room temperature; it is ~30 times higher than in Pt/BaFeO. These strong effects originate from the presence of more pronounced TSSs at low temperatures due to enhanced surface conductivity and reduced bulk conductivity.
拓扑绝缘体中的拓扑表面态（TSSs）有望能够产生自旋轨道转矩，该转矩可切换相邻的铁磁体。如果铁磁体是导电的，这种效应可能不存在，因为它可以完全抑制TSSs，但如果铁磁体是绝缘的，这种效应应该存在。本研究报告了在由拓扑绝缘体BiSe和绝缘铁磁体BaFeO组成的双层结构中，TSSs诱导的开关效应。BiSe中的电荷电流可以上下切换BaFeO中的磁化强度。当通过磁场切换磁化强度时，BiSe中的电流可以将开关场降低约4000 Oe。3 K时的开关效率比室温下高300倍；比Pt/BaFeO中的开关效率高约30倍。这些强烈的效应源于低温下由于表面电导率增强和体电导率降低而出现的更明显的TSSs。
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