重金属/磁性绝缘体异质结在补偿点附近的自旋流输运研究

Heavy metal/magnet insulator heterostructures are rich in physical properties due to spin-orbit coupling and symmetry breaking at the interface, which is one of the frontiers of spintronics. Such heterostructures have various spin-related effects, including spin pumping, spin Seebeck effect, spin Hall magnetoresistance and magnetic proximity effect. And recently, current-induced switching of a perpendicularly magnetized garnet film driven by spin-orbit torque (SOT) has been demonstrated in such heterostructures. In this project, magnetic insulator films with perpendicular magnetic anisotropy and compensation point will be prepared, and the spin transport and SOT of their heterojunctions with heavy metals will be studied near the compensation point. First of all, we will study spin transport phenomena such as the “anomalous Hall effect” near the compensation point, to explore the interaction mechanism between the spin current and the magnetic moment of the insulator at the interface. Then, we will attempt to modulate the spin mixing conductance by doping the sublattice lattice of the magnet insulator. Finally, the current-induced SOT effective field and switching efficiency around the compensation point will be studied. We will try to achieve more efficient current-induced magnetic switching devices based on magnetic insulators.

重金属和磁性绝缘体薄膜组成的异质结，由于界面的强自旋轨道耦合和对称性破缺，具有丰富的物理性质，是当前自旋电子学的前沿研究方向之一。这类体系具有各种自旋相关效应, 包括自旋泵浦效应，自旋塞贝克效应，自旋霍尔磁电阻和磁近邻效应等，最近又在这个体系中实现了基于自旋轨道矩的电流诱导磁化翻转。本项目拟制备同时具有垂直磁各向异性和补偿点的磁性绝缘体薄膜，并研究其与重金属构成的异质结在补偿点附近的自旋输运和自旋轨道矩。拟首先研究其“反常霍尔效应”等自旋输运现象在补偿点附近的变化，以探究自旋流在界面处与绝缘体磁矩的相互作用机制。然后通过磁性次晶格掺杂尝试调控其界面自旋混合电导。最后研究其自旋轨道矩引起的有效场和翻转效率在补偿点附近的变化，尝试实现基于磁性绝缘体的更高效率的电流诱导磁化翻转。

重金属和磁性绝缘体薄膜构成的异质结，因为自旋-轨道耦合和界面对称性破缺，表现出多种新奇物理现象。本项目制备了多种金属/磁性绝缘体异质结，主要研究了其在补偿点附近的自旋流输运、界面自旋轨道耦合和自旋波等。首先，制备了同时具有垂直磁各向异性和补偿点的亚铁磁绝缘体薄膜，测量了其与重金属组成的异质结的反常霍尔效应和自旋霍尔磁电阻效应，这两种效应可作为磁性绝缘体中磁畴状态的读出手段；通过对坡莫合金/氧化铝异质结中界面自旋轨道耦合的研究，我们发现少量的重金属掺杂可以显著的增强界面自旋轨道耦合强度，这可以减少重金属的使用，降低器件成本；磁性绝缘体中的自旋输运性质与其自旋波的性质密切相关，通过理论模拟我们研究了磁绝缘体中自旋波传播的非互易性，并验证了自旋泵浦效应可以高精度地探测线性和非线性自旋波及其色散关系。这些研究为制备基于磁性绝缘体的低功耗自旋电子学器件提供了指导。