Josephson effect in d-wave superconductor junctions in a lattice model

TL;DR

This paper investigates the Josephson effect in d-wave superconductor junctions using a lattice model, revealing diverse temperature behaviors influenced by misorientation angles and interface states, including zero energy states and oscillations.

Contribution

It introduces a lattice model approach to study Josephson currents in d-wave superconductor junctions, highlighting effects of lattice-specific phenomena like wave function oscillations.

Findings

Maximum Josephson current varies with temperature and junction type.

Zero energy states cause low-temperature anomalies in Josephson current.

Lattice-specific wave function oscillations can suppress zero energy states.

Abstract

Josephson current between two d-wave superconductors is calculated by using a lattice model. Here we consider two types of junctions, $i.e.$, the parallel junction and the mirror-type junction. The maximum Josephson current $(J_{c})$ shows a wide variety of temperature ($T$) dependence depending on the misorientation angles and the types of junctions. When the misorientation angles are not zero, the Josephson current shows the low-temperature anomaly because of a zero energy state (ZES) at the interfaces. In the case of mirror-type junctions, $J_c$ has a non monotonic temperature dependence. These results are consistent with the previous results based on the quasiclassical theory. [Y. Tanaka and S. Kashiwaya: Phys. Rev. B \textbf{56} (1997) 892.] On the other hand, we find that the ZES disappears in several junctions because of the Freidel oscillations of the wave function, which is peculiar to the lattice model. In such junctions, the temperature dependence of $J_{c}$ is close to the Ambegaokar-Baratoff relation.