Large and Robust Charge-to-Spin Conversion in Sputtered Weyl Semimetal WTex with Structural Disorder

Xiang Li, Peng Li, Vincent D.-H. Hou, Mahendra DC, Chih-Hung Nien, Fen Xue, Di Yi, Chong Bi, Chien-Min Lee, Shy-Jay Lin, Wilman Tsai, Yuri Suzuki, Shan X. Wang

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Jan 16, 2020
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Received Date: 20th December 19

Topological insulators have recently shown great promise for ultralow-power spin-orbit torque (SOT) devices thanks to their large charge-to-spin conversion efficiency originating from the spin-momentum-locked surface states. Weyl semimetals, on the other hand, may be more desirable due to their spin-polarized surface as well as bulk states, robustness against magnetic and structural disorder, and higher electrical conductivity for integration in metallic magnetic tunnel junctions. Here, we report that sputtered WTex thin films exhibit local atomic and chemical structures of Weyl semimetal WTe2 and host massless Weyl fermions in the presence of structural disorder at low temperatures. Remarkably, we find superior spin Hall conductivity and charge-to-spin conversion efficiency in these sputtered WTex films compared with crystalline WTe2 flakes. Besides, the strength of unidirectional spin Hall magnetoresistance in annealed WTex/Mo/CoFeB heterostructure is up to 20 times larger than typical SOT/ferromagnet bilayers reported at room temperature. We further demonstrate room temperature field-free magnetization switching at a current density as low as 0.97 MA/cm2. These large charge-to-spin conversion properties that are robust in the presence of structural disorder and thermal annealing pave the way for industrial production of Weyl semimetals. Our results open up a new class of sputtered Weyl semimetals for memory and computing based on magnetic tunnel junctions as well as broader planar heterostructures containing SOT/ferromagnet interfaces.

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This is an abstract of a preprint hosted on an independent third party site. It has not been peer reviewed but is currently under consideration at Nature Communications.

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