Kang Min-Gu, Choi Jong-Guk, Jeong Jimin, Park Jae Yeol, Park Hyeon-Jong, Kim Taehwan, Lee Taekhyeon, Kim Kab-Jin, Kim Kyoung-Whan, Oh Jung Hyun, Viet Duc Duong, Jeong Jong-Ryul, Yuk Jong Min, Park Jongsun, Lee Kyung-Jin, Park Byong-Guk
Department of Materials Science and Engineering, KAIST, Daejeon, 34141, Korea.
KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, 02841, Korea.
Nat Commun. 2021 Dec 7;12(1):7111. doi: 10.1038/s41467-021-27459-2.
Spin-orbit coupling effect in structures with broken inversion symmetry, known as the Rashba effect, facilitates spin-orbit torques (SOTs) in heavy metal/ferromagnet/oxide structures, along with the spin Hall effect. Electric-field control of the Rashba effect is established for semiconductor interfaces, but it is challenging in structures involving metals owing to the screening effect. Here, we report that the Rashba effect in Pt/Co/AlO structures is laterally modulated by electric voltages, generating out-of-plane SOTs. This enables field-free switching of the perpendicular magnetization and electrical control of the switching polarity. Changing the gate oxide reverses the sign of out-of-plane SOT while maintaining the same sign of voltage-controlled magnetic anisotropy, which confirms the Rashba effect at the Co/oxide interface is a key ingredient of the electric-field modulation. The electrical control of SOT switching polarity in a reversible and non-volatile manner can be utilized for programmable logic operations in spintronic logic-in-memory devices.
在具有反演对称性破缺的结构中，自旋轨道耦合效应（即 Rashba 效应）与自旋霍尔效应一起，促进了重金属/铁磁体/氧化物结构中的自旋轨道转矩（SOTs）。半导体界面已实现了 Rashba 效应的电场控制，但由于屏蔽效应，在涉及金属的结构中实现这一点具有挑战性。在此，我们报道了 Pt/Co/AlO 结构中的 Rashba 效应可通过电压进行横向调制，从而产生面外 SOTs。这实现了垂直磁化的无场切换以及切换极性的电控制。改变栅极氧化物会反转面外 SOT 的符号，同时保持电压控制磁各向异性的符号不变，这证实了 Co/氧化物界面处的 Rashba 效应是电场调制的关键因素。以可逆和非易失的方式对 SOT 切换极性进行电控制可用于自旋电子逻辑存储器件中的可编程逻辑操作。
