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arXiv · 2503.21391

Andreev bound states and supercurrent in an unconventional superconductor-altermagnetic Josephson junction

Mohammad Alipourzadeh·Yaser Hajati
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Abstract

Motivated by the orientation-dependent properties of d-wave superconductors (SCs), we investigate Andreev bound states (ABSs) and Josephson current in s-wave SC/altermagnet/d-wave SC (S/AM/D) and d-wave SC/altermagnet/d-wave SC (D/AM/D) junctions. The asymmetric S/AM/D junction exhibits a node-less ABSs spectrum with distinct spin states, arising from AM manipulation. In contrast, a symmetric D/AM/D junction with $\pm 45^\circ$-oriented order parameters exhibits a nodal ABSs spectrum, characterized by spin-split sinusoidal curves. This behavior arises from the angular dependence of the d-wave pairing potential, which introduces a $\pi$-shift in the ABSs spectrum of the D/AM/D junction compared to that of conventional S/AM/S junctions. Additionally, the positions of the ABSs nodes in the D/AM/D junction can be controlled by adjusting the length and strength of the AM layer. Analysis of the free energy and Josephson current reveals additional extrema in the free energy at intermediate phase differences, leading to skewness and a non-sinusoidal behavior in the current-phase relationship of both configurations. These zero-supercurrent phase differences can be tuned by adjusting the properties of the AM layer such as AM strength and length. These findings provide new insights into AM-based Josephson junctions.

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Mohammad Alipourzadeh, Yaser Hajati. 2025-03-27. Andreev bound states and supercurrent in an unconventional superconductor-altermagnetic Josephson junction. https://doi.org/10.1103/mj4b-2fnr

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