More than a decade after the first theoretical and experimental studies of the spin Hall conductivity (SHC) of Pt, both its dominant origin and amplitude remain in dispute. Resolving these questions is of fundamental importance for advancing understanding of very strong spin-orbit effects in conducting systems and for maximizing the spin Hall effect for energy-efficient spintronics applications. Here, we report the experimental determination of the rapid variation of the intrinsic SHC of Pt with the carrier lifetime (τ) in the dirty-metal regime by incorporating finely dispersed MgO inter-site impurities into the Pt while maintaining the essential elements of its band structure (face-centered-cubic order). This findings conclusively validate the theoretical prediction that the SHC in Pt in the dirty-metal regime should be dominated by the intrinsic Berry curvature contribution and should decrease rapidly with shortening τ. This also establishes the limit to which the spin Hall ratio θSH of pure Pt can be increased by shortening τ. When the spin backflow at the Pt/ferromagnet interface due to the finite interfacial spin-mixing conductance is taken into account, the amplitude of the intrinsic SHC of Pt in the clean limit is found to be at least 1.6x10^6 (h_bar/2e) Ω-1 m-1, more than 3.5 times greater than the available theoretical predictions. Our work also establishes a compelling spin Hall metal Pt0.6(MgO)0.4 that combines a giant θSH (0.73) with a moderate resistivity (74 μΩ cm), a strong Dzyaloshinskii-Moriya interaction, easy growth, and good integration compatibility for spintronics technology.
Above-room-temperature giant thermal conductivity switching in spintronic multilayer
热开关是一种有效的主动热流控制方法，近年来在纳米级热管理技术方面受到越来越多的关注。在磁性和自旋电子材料中，热导率取决于磁化结构：这是磁热阻效应。在这里，我们表明，外延Cu/Co $_{50}$ Fe $_{50}$多层膜具有巨大的磁场诱导调制的跨平面热导率。Cu/Co $_{50}$ Fe $_{50}$多层膜在室温下的磁热电阻比达到150%，远高于以往的最高值。虽然该比值随温度的升高而减小，但在400 K以下仍出现~100%的巨磁热电阻效应。观察到Cu/Co $_{50}$ Fe $_{50}$多层膜的热导率的磁场依赖性比跨平面电导率的磁场依赖性大约两倍。巨磁热电阻效应的观察阐明了自旋电子多层膜作为热开关器件的潜力。
Linear and nonlinear Hall conductivity in presence of interaction and disorder
非线性霍尔效应的理论是由I. Sodemann和L. Fu [Phys. Rev. Lett. 115，216806（2015）]在半经典框架中：其中，该效应表现为布洛赫电子的几何性质，源于它们的异常速度。在这里，我提出了一个更一般的理论，解决相关和/或非晶态系统以及，线性和非线性霍尔电导率的表达式起源于多电子异常速度。独立电子的结果检索作为特殊情况。
Maximizing the spin-orbit torque efficiency of Pt/Ti multilayers by optimization of the tradeoff between the intrinsic spin Hall conductivity and carrier lifetime
