Dynamic spin-triplet order induced by alternating electric fields in superconductor-ferromagnet-superconductor Josephson junctions

TL;DR

This paper demonstrates how alternating electric fields can induce dynamic spin-triplet superconducting order in superconductor-ferromagnet-superconductor Josephson junctions, enabling new control over quantum states.

Contribution

It introduces a mechanism where time-dependent electric fields convert static p-wave order into dynamic triplet correlations via ferromagnetism and spin-orbit coupling.

Findings

Critical current is proportional to electromagnetic power.

Proposes a Josephson transistor switchable by ac voltage.

Designs photo-magnetic SQUID devices with irradiation-induced spontaneous magnetic fields.

Abstract

Dynamic states offer extended possibilities to control the properties of quantum matter. Recent efforts are focused on studying the ordered states which appear exclusively under the time-dependent drives. Here we demonstrate a class of systems which feature dynamic spin-triplet superconducting order stimulated by the alternating electric field. The effect is based on the interplay of ferromagnetism, interfacial spin-orbital coupling (SOC) and the condensate motion driven by the field, which converts hidden static p-wave order, produced by the joint action of the ferromagnetism and the SOC, into dynamical s-wave equal-spin triplet correlations. We demonstrate that the critical current of Josephson junctions hosting these states is proportional to the electromagnetic power, supplied either by the external irradiation or by the ac current source. Based on these unusual properties we propose the scheme of a Josephson transistor which can be switched by the ac voltage and demonstrates an even-numbered sequence of Shapiro steps. Combining the photo-active Josephson junctions with recently discovered Josephson phase batteries we find photo-magnetic SQUID devices which can generate spontaneous magnetic fields while being exposed to irradiation.