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arXiv 2402.08263cond-mat.mes-hallcond-mat.mtrl-scicond-mat.supr-con
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反铁磁体中的交叉安德列夫反射

Crossed Andreev reflection in altermagnets

Sachchidanand Das, Abhiram Soori

AI总结:

本研究针对交叉安德列夫反射(CAR)探测受电子隧穿阻碍的问题,提出在超导体两侧放置两个旋转90°的反铁磁体的构型,计算表明该构型可显著增强CAR,电导率随超导体长度呈法布里-珀罗式振荡。

摘要:

交叉安德列夫反射(Crossed Andreev reflection, CAR)是发生在连接两个金属引线的超导体(superconductor, SC)中的一种散射现象,其中入射到SC一侧的电子会以空穴的形式出现在另一侧。尽管CAR具有重要意义,但其探测常被普遍存在的电子隧穿(electron tunneling, ET)所阻碍,在ET过程中入射电子会以电子的形式从对侧射出。一种增强CAR相对ET占比的方法是在SC两侧使用两个反平行的铁磁体,但该方法受限于铁磁体的低极化率,且需要施加磁场。反铁磁体(altermagnets, AMs)由于两种自旋具有截然不同的费米面,为探测和增强CAR提供了一条有前景的途径。在此,我们提出一种构型:在SC两侧使用两个相互旋转90°的AMs来增强CAR。我们采用Landauer-Büttiker散射方法计算了AM-SC-AM结的局域和非局域电导率。研究结果表明,在AMs的强相中,CAR在非局域输运中占绝对主导地位;在弱相中,与AMs处于正常金属相的情形相比,当反铁磁参数取较大值时,CAR可表现出显著增强。电导率随SC长度的变化呈现出类似法布里-珀罗(Fabry-Pérot)干涉的振荡特性。

英文摘要:

Crossed Andreev reflection (CAR) is a scattering phenomenon occurring in a superconductor (SC) connected to two metallic leads, where an incident electron on one side of the SC emerges on the opposite side as a hole. Despite its significance, CAR detection is often impeded by the prevalent electron tunneling (ET), wherein the incident electron exits on the opposing side as an electron. One approach to augment CAR over ET involves employing two antiparallel ferromagnets across the SC. However, this method is constrained by the low polarization in ferromagnets and necessitates the application of a magnetic field. Altermagnets (AMs) present a promising avenue for detecting and enhancing CAR due to their distinct Fermi surfaces for the two spins. Here, we propose a configuration utilizing two AMs rotated by $90^{\circ}$ with respect to each other on either side of an SC to enhance CAR. We calculate local and nonlocal conductivities across the AM-SC-AM junction using the Landauer-Büttiker scattering approach. Our findings reveal that in the strong phase of AMs, CAR overwhelmingly dominates nonlocal transport. In the weak phase, CAR can exhibit significant enhancement for larger values of the altermagnetic parameter compared to the scenario where AMs are in the normal metallic phase. As a function of the length of the SC, the conductivities exhibit oscillations reminiscent of Fabry-Pérot interference.

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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