论文标题
自然氧化的多晶Taas薄膜的巨型自旋扭矩效率
Giant spin torque efficiency in naturally oxidized polycrystalline TaAs thin films
论文作者
论文摘要
我们报告了在室温下在Weyl Semimetal/Ferromagnet异质结构中均具有氧化和原始界面的有效电荷到旋转转换的测量。 Weyl半准Taas的多晶膜由（001）GAAS上的分子束外伸肌生长，并与金属Ferromagnet（Ni $ _ {0.8} $ fe $ _ = $ _ {0.2} $）与金属的Ferromagnet（Ni $ _ {0.8} $具有氧化界面样品中的旋转扭矩铁磁共振（ST-FMR）的测量结果，产生的自旋扭矩效率高达$ξ_{\ MATHRM {fmr}} = 0.45 \ pm 0.25 \ pm 0.25 $，对于8 nm ni $ ni $ $ _ {0.8} $ _ {0.8} $ _ {0.8} $ fe $ $ $ $ _ cou;通过在这些样品中研究ST-FMR，具有不同的Ni $ _ {0.8} $ fe $ _ {0.2} $ layer layer厚度，我们提取了一种阻尼的扭矩效率，高达$ξ_ {\ Mathrm {dl}} = 1.36 = 1.36 \ pm pm 0.66 $。在具有原始（未氧化）界面的样品中，自旋扭矩效率的迹象与在氧化样品中观察到的迹象相反（$ξ_ {\ mathrm {fmr}} = - 0.27 \ 0.27 \ pm 0.14 $，对于5 nm ni $ _ {0.8} $ _ {0.8} $ fe $ _ {0.2 $ _ {0.2} $ {0.2} $ soldness）。我们还在自旋厅电导率上找到一个下限（$ 424 \ pm 110 \ frac {\ hbar} {e} $ s/cm），这与TAAS的单晶韦伊尔半微分状态的理论预测令人惊讶地一致。
We report the measurement of efficient charge-to-spin conversion at room temperature in Weyl semimetal/ferromagnet heterostructures with both oxidized and pristine interfaces. Polycrystalline films of the Weyl semimetal, TaAs, are grown by molecular beam epitaxy on (001) GaAs and interfaced with a metallic ferromagnet (Ni$_{0.8}$Fe$_{0.2}$). Spin torque ferromagnetic resonance (ST-FMR) measurements in samples with an oxidized interface yield a spin torque efficiency as large as $ξ_{\mathrm{FMR}}=0.45\pm 0.25$ for a 8 nm Ni$_{0.8}$Fe$_{0.2}$ layer thickness. By studying ST-FMR in these samples with varying Ni$_{0.8}$Fe$_{0.2}$ layer thickness, we extract a damping-like torque efficiency as high as $ξ_{\mathrm{DL}}=1.36\pm 0.66$. In samples with a pristine (unoxidized) interface, the spin torque efficiency has opposite sign to that observed in oxidized samples ($ξ_{\mathrm{FMR}}=-0.27\pm 0.14$ for a 5 nm Ni$_{0.8}$Fe$_{0.2}$ layer thickness). We also find a lower bound on the spin Hall conductivity ($424 \pm 110 \frac{\hbar}{e}$ S/cm) which is surprisingly consistent with theoretical predictions for the single crystal Weyl semimetal state of TaAs.
