We demonstrate that the magnetic anisotropy in SrRuO₃ (SRO) ultrathin films can be well controlled by thickness or electrical modulations: The easy axis (preferred magnetization direction) of a SRO ultrathin film can be switched between out-of-plane and in-plane magnetization either by altering the film thickness or by tuning the doping level through applying a gate voltage or chemical doping. Such a capability to manipulate the magnetocrystalline anisotropy energy (MCAE) is given by the spin–orbit coupling (SOC)-induced energy splitting in the spin-polarized quantum well states (QWSs) near the Fermi level. These QWSs are susceptible to the intrinsic spin–orbit interaction and thus drive a large energy discrepancy when an SRO ultrathin film rotates its magnetization direction. As a result of the MCAE nature, a SRO film has a magnetic anisotropy approximately an order of magnitude larger than those in 3d-ferromagnet ultrathin films and its easy-axis direction depends on the film thickness, gate voltage, and substrate. This tunable large magnetic anisotropy in SRO ultrathin films provides an excellent route toward advanced spintronic devices such as storage and memory devices.

中文翻译：

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由于纳米厚 SrRuO ₃薄膜中的自旋极化量子阱共振，第一性原理计算预测可调谐大磁各向异性：对自旋电子器件的影响

我们证明了 SrRuO ₃中的磁各向异性(SRO) 超薄膜可以通过厚度或电调制很好地控制：SRO 超薄膜的易轴（优选磁化方向）可以通过改变薄膜厚度或通过通过施加栅极电压或化学掺杂来调整掺杂水平。这种操纵磁晶各向异性能量 (MCAE) 的能力是由费米能级附近的自旋极化量子阱态 (QWS) 中的自旋轨道耦合 (SOC) 诱导的能量分裂提供的。这些 QWS 容易受到固有的自旋轨道相互作用的影响，因此当 SRO 超薄膜旋转其磁化方向时会产生很大的能量差异。由于 MCAE 的性质，SRO 薄膜的磁各向异性比 3d 铁磁超薄膜大一个数量级，其易轴方向取决于薄膜厚度、栅极电压和基板。SRO 超薄膜中这种可调谐的大磁各向异性为先进的自旋电子器件（如存储和存储器件）提供了极好的途径。