Spin-charge conversion induced magnetoresistance and related applications
|イベント概要||Prof. Yihong Wu (National University of Singapore)
This talk is divided into two parts. In the first part, I will discuss our recent finding of an MR induced by the anomalous Hall effect (AHE) in a ferromagnet.1 When a charge current flows in a ferromagnet, both transverse charge and spin accumulations will occur at boundaries of the sample at steady state. The spin accumulation in turn can induce a spin current either in an adjacent material or in the ferromagnet itself due to backflow of spin from the boundary. We demonstrate that the spin accumulation, subsequent spin backflow, and spin-charge conversion can give rise to a different type of spin current related magnetoresistance, dubbed as the anomalous Hall magnetoresistance (AHMR), which has the same angular dependence as the recently discovered spin Hall magnetoresistance (SMR). The anomalous Hall magnetoresistance is observed in four types of samples: co-sputtered (Fe1-xMnx)0.6Pt0.4, Fe1-xMnx/Pt multilayer, Fe1-xMnx with x = 0.17 – 0.65 and Fe, and analyzed using the drift-diffusion model. The AHMR provides an alternative route to study charge-spin conversion in ferromagnets and to exploit it for potential spintronic applications. In the 2nd part, I will present an all-in-one SMR sensor which exploits the spin-orbit toque (SOT) and SMR in Pt/NiFe heterostructures. The SMR sensor utilizes the SOT effective field as the built-in linearization mechanism2-4, which effectively replaces the sophisticated linearization mechanism employed in conventional MR sensors. By introducing a new magnetic excitation mechanism, which is built-in in the structure itself, we were able to achieve a sensor which is essentially free of DC offset and negligible hysteresis, and importantly, all these are realized in an extremely simple structure. We will demonstrate a few proof-of-concept applications of the SMR sensor.