Emergent reactance induced by the deformation of a current-driven skyrmion lattice

TL;DR

This paper demonstrates emergent reactance phenomena in skyrmion lattices, revealing how skyrmion deformation during creep motion induces electric fields and phase shifts in AC currents, advancing understanding of skyrmion dynamics.

Contribution

It provides the first experimental observation of emergent reactance in skyrmion-hosting material MnSi, linking skyrmion deformation to emergent electric fields and reactance effects.

Findings

Observation of longitudinal and Hall reactance signals during skyrmion creep motion

Attribution of Hall reactance to emergent electric fields from skyrmion inertial motion

Identification of longitudinal reactance from deformation-induced emergent electric fields

Abstract

The interaction between conduction electrons and spin textures gives rise to remarkable phenomena associated with the Berry phase. The Berry phase acquired by conduction electrons acts as an emergent electromagnetic field, facilitating phenomena analogous to classical electromagnetism, such as the Lorentz force and electromagnetic induction. Magnetic skyrmions, spin vortices with non-trivial topology, serve as a key platform for such studies. For example, non-trivial transport responses are recognized as being induced by the emergent Lorentz force and the emergent electromagnetic induction. Despite remarkable progress in skyrmion physics, emergent reactance, in which the phase of an applied AC current is modified by emergent electromagnetism, has not been thoroughly investigated. Here, we report emergent reactance in the prototypical skyrmion-hosting material, MnSi. We observe longitudinal and Hall reactance signals as the skyrmion lattice undergoes creep motion, in which the skyrmions deform while moving. The Hall reactance is attributed to the emergent electric field associated with the inertial translational motion arising from the skyrmion effective mass. In contrast, the longitudinal reactance results from the emergent electric fields generated by the phason and spin-tilting modes excited by their deformation. Our findings shed light on the internal deformation degrees of freedom in skyrmions as a important factor for efficient generation of the emergent electric field.