Peng Cheng-Wei, Liao Wei-Bang, Chen Tian-Yue, Pai Chi-Feng
Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan.
Center of Atomic Initiative for New Materials, National Taiwan University, Taipei 10617, Taiwan.
ACS Appl Mater Interfaces. 2021 Apr 7;13(13):15950-15957. doi: 10.1021/acsami.1c03530. Epub 2021 Mar 26.
Spin-orbit torques (SOTs) from transition metal dichalcogenide systems (TMDs) in conjunction with ferromagnetic materials are recently found to be attractive in spintronics for their versatile features. However, most of the previously studied crystalline TMDs are prepared by mechanical exfoliation, which limits their potentials for industrial applications. Here, we show that amorphous WTe heterostructures deposited by magnetron sputtering possess a sizable damping-like SOT efficiency of ξ ≈ 0.20 and low damping constant of α = 0.009 ± 0.001. Only an extremely low critical switching current density of ≈ 7.05 × 10 A/m is required to achieve SOT-driven magnetization switching. The SOT efficiency is further proved to depend on the W and Te relative compositions in the co-sputtered WTe samples, from which a sign change of ξ is observed. In addition, the electronic transport in amorphous WTe is found to be semiconducting and is governed by a hopping mechanism. With the above advantages and rich tunability, amorphous and semiconducting WTe serves as a unique SOT source for future spintronics applications.
最近发现，过渡金属二硫属化物体系（TMDs）与铁磁材料相结合产生的自旋轨道转矩（SOTs）因其多功能特性而在自旋电子学中颇具吸引力。然而，大多数先前研究的晶体TMDs是通过机械剥离制备的，这限制了它们在工业应用中的潜力。在此，我们表明，通过磁控溅射沉积的非晶WTe异质结构具有相当大的类阻尼SOT效率，ξ≈0.20，以及低阻尼常数α = 0.009±0.001。实现SOT驱动的磁化翻转仅需极低的临界开关电流密度，约为7.05×10 A/m。进一步证明，SOT效率取决于共溅射WTe样品中W和Te的相对组成，从中观察到ξ的符号变化。此外，发现非晶WTe中的电子输运具有半导体特性，且受跳跃机制支配。凭借上述优点和丰富的可调性，非晶和半导体WTe可作为未来自旋电子学应用中独特的SOT源。
