Light-modulated Josephson effect in Kekul\'e patterned graphene

TL;DR

This paper theoretically investigates how circularly polarized light influences the Josephson effect in Kekul'e patterned graphene, revealing light-induced $\pi$-states and the suppression of such states depending on the pattern type.

Contribution

It introduces a novel theoretical framework for controlling Josephson junction states in Kekul'e patterned graphene using light.

Findings

Kekul'e-O pattern enables light-induced $\pi$-states via Fermi momentum splitting.

Kekul'e-Y pattern suppresses momentum splitting, maintaining 0-states.

Critical current depends on junction length and light parameters.

Abstract

We theoretically study the Josephson effect in a superconductor/normal metal/superconductor junction based on Kekul\'e patterned graphene. For the Kekul\'e-O patterned junctions, a Fermi momentum-splitting Andreev reflection at the interface can be induced by the off-resonant circularly polarized light applied in the normal region, which results in the possible $\pi$-state. In contrast, for the Kekul\'e-Y patterned junctions, the Fermi momentum-splitting Andreev reflection is strongly suppressed due to the valley-momentum locking and the junction always exhibits the 0-state. The dependence of the critical current on the junction length and the illumination parameter of the light field is also presented in detail.