Optical spin-orbit torque in heavy metal-ferromagnet heterostructures
Optical spin-orbit torque in heavy metal-ferromagnet heterostructures
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DOI：
10.1038/s41467-020-15247-3
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发表时间：
2020-03-20
影响因子：
16.6
通讯作者：
Lee, Hyun-Woo
中科院分区：
文献类型：
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作者：
Choi, Gyung-Min;Oh, Jung Hyun;Lee, Hyun-Woo
在非磁性材料中，通过自旋-轨道相互作用产生的自旋电流是自旋电子学的核心。当产生的自旋电流注入铁磁体时，它产生自旋轨道扭矩，并有效地操纵磁化。光学产生的自旋流有望在操纵速度方面优于电自旋流。在这里，我们报道了重金属/铁磁异质结中的光学自旋轨道扭矩。重金属强烈的自旋-轨道耦合导致光激载流子自旋极化，而它们从重金属到铁磁体的输运引起磁化扭矩。我们的结果表明，重金属不仅可以在电学上产生自旋轨道扭矩，还可以在光学上产生自旋轨道扭矩。已知，当面内电流注入与铁磁(FM)层接触的重金属(HM)层时，可以对该FM层中的自旋施加扭矩。在这里，作者证明了在没有电流注入的情况下，可以通过将圆偏振光照射到HM上来产生扭矩。
Spin current generation through the spin-orbit interaction in non-magnetic materials lies at the heart of spintronics. When the generated spin current is injected to a ferromagnet, it produces spin-orbit torque and manipulates magnetization efficiently. Optically generated spin currents are expected to be superior to their electrical counterparts in terms of the manipulation speed. Here we report optical spin-orbit torques in heavy metal/ferromagnet heterostructures. The strong spin-orbit coupling of heavy metals induces photo-excited carriers to be spin-polarized, and their transport from heavy metals to ferromagnets induces a torque on magnetization. Our results demonstrate that heavy metals can generate spin-orbit torque not only electrically but also optically. It is known that torques can be exerted on spins in a ferromagnet (FM) layer when an in-plane electric current is injected into a heavy metal (HM) layer in contact with the FM layer. Here, the authors demonstrate that torques can be generated without the current injection by shining instead circularly polarized light on the HM.