2025/01/21 by Zhao, Wenjun, Fukaya, Yuri, Burset, Pablo +3 · 1 citation
#FOS: Physical sciences #Superconductivity (cond-mat.supr-con)
paper · doi:10.48550/arxiv.2501.12141
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 dx2-y2-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 dxy-altermagnet only features de Gennes-Saint-James states in the long junction. Moreover, the well-known features such as V-shape conductance for dx2-y2 pairings and zero-biased conductance peak for dxy pairings are not affected by the strength of dxy-altermagnetism in the short junction. We also study the Josephson current-phase relation I(φ) of d-wave superconductor/altermagnet/d-wave superconductor hybrids, where φ is the macroscopic phase difference between two d-wave superconductors. In symmetric junctions, we obtain anomalous current phase relation such as a 0-π 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 dx2-y2-superconductor/altermagnet/dxy-superconductor junction when the symmetry of altermagnetic order parameter is neither dx2-y2- nor dxy-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.