Strain driven conducting domain walls in a Mott insulator

TL;DR

This paper demonstrates that in narrow-gap correlated insulators like GaV4S8, local strain gradients at domain walls can induce conductivity independently of charge screening, broadening the scope of nanoelectronic applications.

Contribution

It reveals a new mechanism where strain gradients, not charge screening, drive conductivity at domain walls in correlated insulators, expanding material possibilities.

Findings

Conductivity at domain walls in GaV4S8 is driven by strain gradients.

The mechanism is independent of traditional charge screening models.

Structural and magnetic domain walls can become conductive through strain effects.

Abstract

Rewritable nanoelectronics offers new perspectives and potential to both fundamental research and technological applications. Such interest has driven the research focus into conducting domain walls: pseudo 2D conducting channels that can be created, positioned, and deleted in situ. However, the study of conductive domain walls is largely limited to wide-gap ferroelectrics, where the conductivity typically arises from changes in charge carrier density, due to screening charge accumulation at polar discontinuities. This work shows that, in narrow-gap correlated insulators with strong charge lattice coupling, local strain gradients can drive enhanced conductivity at the domain walls, removing polar discontinuities as a criteria for conductivity. By combining different scanning probe microscopy techniques, we demonstrate that the domain wall conductivity in GaV4S8 does not follow the established screening charge model but rather arises from the large surface reconstruction across the Jahn-Teller transition and the associated strain gradients across the domain walls. This mechanism can turn any structural, or even magnetic, domain wall conducting, if the electronic structure of the host is susceptible to local strain gradients, drastically expanding the range of materials and phenomena that may be applicable to domain wall based nanoelectronics.