Nonequilibrium charge density wave ordering from anomalous velocity in itinerant helical magnets

TL;DR

This paper demonstrates that the Karplus-Luttinger anomalous velocity causes electric-field-induced charge density waves in noncollinear itinerant magnets like MnSi, revealing novel nonequilibrium many-electron phenomena.

Contribution

It introduces a mechanism where anomalous velocity induces charge density waves in helical magnets, linking topological effects to nonequilibrium charge order.

Findings

Charge accumulation leads to charge density waves with helix period.

Anomalous velocity effects are significant in nearly ferromagnetic noncollinear magnets.

The study connects topological anomalous velocity to many-electron physics phenomena.

Abstract

The Karplus-Luttinger anomalous velocity is shown to lead to electric-field-induced charge accumulation in nearly ferromagnetic noncollinear magnets with itinerant electrons, like $MnSi$. For helical magnetic ordering, the balance between this accumulation and the Coulomb interaction leads to a nonequilibrium charge density wave state with the period of the helix, even when such accumulation is forbidden by an approximate gauge-like symmetry in the absence of electric field. We compute the strength of such charge accumulation as an example of how unexpected many-electron physics is induced by the inclusion of the one-electron Karplus-Luttinger term whenever the local exchange field felt by conduction electrons does not satisfy the current-free Maxwell equations.