Orientation-dependent transport in junctions formed by $d$-wave altermagnets and $d$-wave superconductors

Abstract

We investigate de Gennes-Saint-James states and Josephson effect in hybrid junctions based on $d$-wave altermagnet and $d$-wave superconductor. Even though these states are associated to long junctions, we find that the $d_{x^2-y^2}$-altermagnet in a normal metal/altermagnet/$d$-wave superconductor junction forms de Gennes-Saint-James states in a short junction due to an enhanced mismatch between electron and hole wave vectors. As a result, the zero-bias conductance peak vanishes and pronounced resonance spikes emerge in the subgap conductance spectra. By contrast, the $d_{xy}$-altermagnet only features de Gennes-Saint-James states in the long junction. Moreover, the well-known features such as V-shape conductance for $d_{x^2-y^2}$ pairings and zero-biased conductance peak for $d_{xy}$ pairings are not affected by the strength of $d_{xy}$-altermagnetism in the short junction. We also study the Josephson current-phase relation $I(\phi )$ of $d$-wave superconductor/altermagnet/$d$-wave superconductor hybrids, where $\phi$ is the macroscopic phase difference between two $d$-wave superconductors. In symmetric junctions, we obtain anomalous current phase relation such as a $0$-$\pi$ transition by changing either the orientation or the magnitude of the altermagnetic order parameter and dominant higher Josephson harmonics. Interestingly, we find the first-order Josephson coupling in an asymmetric $d_{x^2-y^2}$-superconductor/altermagnet/$d_{xy}$-superconductor junction when the symmetry of altermagnetic order parameter is neither $d_{x^2-y^2}$- nor $d_{xy}$-wave. We present the symmetry analysis and conclude that the anomalous orientation-dependent current-phase relations are ascribed to the peculiar feature of the altermagnetic spin-splitting field.

10 pages, 5 figures

References in corpus (9)

• Antiferromagnetism in RuO${}_2$ as $d$-wave Pomeranchuk instability
• Odd-frequency pairing in normal metal/superconductor junctions
• Altermagnetism with Non-collinear Spins
• Anomalous Hall effect in $\kappa$-type organic antiferromagnets
• Theory of Majorana zero modes in unconventional superconductors
• Orientation-dependent Josephson effect in spin-singlet superconductor/altermagnet/spin-triplet superconductor junctions
• Josephson effect and odd-frequency pairing in superconducting junctions with unconventional magnets
• Classification of pair symmetries in superconductors with unconventional magnetism
• Anomalous Josephson current in superconducting topological insulator

Cited by in corpus (12)

• Superconducting phenomena in systems with unconventional magnets
• Tuning of altermagnetism by strain
• All-electrically controlled spintronics in altermagnetic heterostructures
• Floquet engineering spin triplet states in unconventional magnets
• Andreev bound states and supercurrent in an unconventional superconductor-altermagnetic Josephson junction
• Light-induced odd-parity altermagnets on dimerized lattices
• Light-induced Floquet spin-triplet Cooper pairs in unconventional magnets
• Tunneling conductance in superconducting junctions with $p$-wave unconventional magnets breaking time-reversal symmetry
• Nonlocal Josephson diode effect in minimal Kitaev chains
• Engineering subgap states in superconductors by the symmetry of altermagnetism
• The Josephson effect in Fibonacci superconductors
• Time reversal reserved spin valve and spin transistor based on unconventional $p$-wave magnets