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arXiv 2201.01750cond-mat.supr-concond-mat.mes-hall
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二维$s$波超导体中束缚态的准粒子聚焦

Quasiparticle focusing of bound states in two-dimensional $s$-wave superconductors

Mateo Uldemolins, Andrej Mesaros, Pascal Simon

摘要:

超导衬底上的磁性杂质在带隙中诱导出Yu-Shiba-Rusinov(YSR)束缚态,其复杂的空间结构决定了设计集体杂质态的可能性.利用鞍点近似方法研究了二维带隙超导体中产生YSR态的散射过程。此外,我们开发了一个理论,通过一个简单的解析表达式,在一个二维主机中的正常电子的任意能量色散的YSR状态的空间特征。也就是说,我们发现,费米面的平坦部分与大的费米速度增强的局域态密度(LDOS)周围的杂质。我们的分析近似是定量准确的紧束缚计算不同的费米表面的各种晶格,它允许预测的形状和取向的扫描隧道光谱实验中观察到的YSR状态。我们用一个$\mathrm{NbSe}_2$模型来说明我们的结果。

英文摘要:

A magnetic impurity on a superconducting substrate induces in-gap Yu-Shiba-Rusinov (YSR) bound states, whose intricate spatial structure crucially influences the possibilities of engineering collective impurity states. By means of a saddle-point approximation we study the scattering processes giving rise to YSR states in gapped, two-dimensional superconductors. Further, we develop a theory which relates through a simple analytical expression an arbitrary energy dispersion of normal electrons in a two-dimensional host to the spatial features of the YSR states. Namely, we find that flatter segments of the Fermi surface with large Fermi velocity enhance the local density of states (LDOS) around the impurity. Our analytical approximation is quantitatively accurate against tight-binding calculations on various lattices with different Fermi surfaces, and it allows to predict the shape and orientation of YSR states observed in scanning tunneling spectroscopy experiments. We illustrate our results with a model of $\mathrm{NbSe}_2$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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