Josephson coupling through a magnetic racetrack

TL;DR

This paper explores how a magnetic domain wall in a ferromagnetic racetrack influences Josephson coupling, enabling control of supercurrent and phase transitions for superconducting memory devices.

Contribution

It demonstrates the control of Josephson critical current via domain wall position, revealing new mechanisms for superconducting racetrack device design.

Findings

Supercurrent distribution is highly sensitive to domain wall position and orientation.

Josephson critical current $I_c$ can be tuned by moving the domain wall.

Pronounced $0$--$ ext{pi}$ transitions are observed with domain wall manipulation.

Abstract

We investigate the Josephson coupling between two superconducting electrodes connected by a ferromagnetic racetrack hosting a Bloch-like domain wall (DW). We show that the interplay between superconductivity and the DW leads to highly non-trivial spatial distributions of the supercurrent, including the formation of current loops and a strong sensitivity to the DW position and orientation. We further demonstrate that the Josephson critical current $I_c$ can be efficiently controlled by the DW position along the racetrack, exhibiting pronounced variations and tunable $0$--$\pi$ transitions. These results provide clear design principles for superconducting racetrack devices and establish domain walls as a viable control element for readout schemes in racetrack memory architectures.