论文标题
从铁磁绝缘子到具有界面的Andfacial Andreev Bound-States的旋转泵送
Spin-pumping from a ferromagnetic insulator to an unconventional superconductor with interfacial Andreev bound-states
论文作者
论文摘要
最近在实验中观察到了从铁磁绝缘子到具有$ D $ - 波超导订单参数的高$ T_C $超导体的旋转泵。已知这种非常规的超导顺序可为某些晶体学取向产生界面结合状态。在这里，我们提出了一种方法，该方法可用于研究旋转泵送成非常规超导体，包括界面结合态的作用。例如，我们确定$ d $ - 波订单参数相对的晶体学方向如何改变旋转泵送效果。我们发现，与其他超导状态相比，在低温下，在低温下，旋转泵浦效果略有增强。但是，对于此类方向而言，自旋泵化效果并未显示出接近$ t_c $的连贯峰，而是所有$ t $的正常状态值仍然小。对于不托管界面结合状态的方向，我们发现与超导间隙相比，在频率很小的频率下，泵送的自旋电流可以增加到正常状态旋转电流的几倍。我们的结果表明，根据界面相对于界面相对的非常规超导顺序参数的晶体学方向，自旋倾斜依赖于频率和温度变化。
Spin-pumping from a ferromagnetic insulator into a high-$T_c$ superconductor with a $d$-wave superconducting order parameter has recently been experimentally observed. Such unconventional superconducting order is known to produce interfacial bound-states for certain crystallographic orientations. Here, we present a methodology which can be used to study spin-pumping into unconventional superconductors, including the role of interfacial bound-states. As an example, we determine how the crystallographic orientation of the $d$-wave order parameter relative the interface changes the spin-pumping effect. We find that the spin-pumping effect is slightly enhanced at low temperatures for orientations hosting interfacial bound-states compared to other superconducting states. However, the spin-pumping effect does not show a coherence peak close to $T_c$ for such orientations, and instead remains smaller than the normal state value for all $T$. For orientations not hosting interfacial bound-states, we find that the pumped spin current can be increased to several times the normal-state spin current at frequencies that are small compared to the superconducting gap. Our results show that the spin-pumping dependency on frequency and temperature changes qualitatively depending on the crystallographic orientation of unconventional superconducting order parameters relative the interface.
