Observation of converse flexoelectric effect in topological semimetals

TL;DR

This paper reports the discovery of a giant flexoelectric effect in topological semimetals, revealing a new electromechanical coupling in metals that could enable advanced nanoscale sensors and energy harvesters.

Contribution

It demonstrates the existence of a converse flexoelectric effect in centrosymmetric topological semimetals, expanding the understanding of electromechanical phenomena in metallic systems.

Findings

Giant elastic deformation observed in (V,Mo)Te2 under electric current

Flexoelectric effect attributed to Berry-phase in topological semimetals

No similar effect in trivial semimetal TiTe2

Abstract

A strong coupling between electric polarization and elastic deformation in solids is an important factor in creating useful electromechanical nanodevices. Such coupling is typically allowed in insulating materials with inversion symmetry breaking as exemplified by the piezoelectric effect in ferroelectric materials. Therefore, materials with metallicity and centrosymmetry have tended to be out of scope in this perspective. Here, we report the observation of giant elastic deformation by the application of an alternating electric current in topological semimetals (V,Mo)Te2, regardless of the centrosymmetry. Considering the crystal and band structures and the asymmetric measurement configurations in addition to the absence of the electromechanical effect in a trivial semimetal TiTe2, the observed effect is discussed in terms of a Berry-phase-derived converse flexoelectric effect in metals. The observation of the flexoelectric effect in topological semimetals paves a way for a new type of nanoscale electromechanical sensors and energy harvesting.