Spin Supercurrent, Magnetization Dynamics, and Phi-State in Spin-Textured Josephson Junctions

TL;DR

This paper explores how spin-polarized supercurrents interact with magnetic textures in Josephson junctions, revealing phase-controlled magnetization switching and the emergence of phi-states with anomalous supercurrents.

Contribution

It introduces a theoretical framework for understanding spin-supercurrent interactions with magnetization textures in various Josephson junction models, highlighting phase control of magnetization and novel phi-states.

Findings

Supercurrent can induce magnetization switching controlled by phase difference.

Chiral symmetry breaking and interface scattering create a phase battery effect.

System exhibits a phi-junction with an anomalous supercurrent at zero phase.

Abstract

The prospect of combining the dissipationless nature of superconducting currents with the spin-polarization of magnetic materials is interesting with respect to exploring superconducting analogues of topics in spintronics. In order to accomplish this aim, it is pivotal to understand how spin-supercurrents interact dynamically with magnetization textures. We investigate the appearance of a spin-supercurrent and the resulting magnetization dynamics in a textured magnetic Josephson current by using three experimentally relevant models: i) a S/F/S junction with spin-active interfaces, ii) a S/F1/F2/F3/S Josephson junction with a ferromagnetic trilayer, and iii) a Josephson junction containing a domain wall. In all of these cases, the supercurrent is spin-polarized and exerts a spin-transfer torque on the ferromagnetic interlayers which causes magnetization dynamics. Using a scattering matrix formalism in the clean limit, we compute the Andreev-bound states and free energy of the system which is used to solve the Landau-Lifshiftz-Gilbert equation. We compute both how the inhomogeneous magnetism influences the phase-dependence of the charge supercurrent as well as the magnetization dynamics caused by the spin-supercurrent. Using a realistic experimental parameter set, we find that the supercurrent can induce magnetization switching that is controlled by the superconducting phase difference. Moreover, we demonstrate that the combined effect of chiral spin symmetry breaking and interface scattering causes the system to act as a phase battery that may supply any superconducting phase difference phi in the ground state. Such a phi junction is accompanied by an anomalous supercurrent appearing even at zero phase difference, and we demonstrate that the flow direction of this current is controlled by the chirality of the magnetization configuration.