Novel Observation of Piezoelectricity in VO2

TL;DR

This paper reports the first observation of piezoelectricity in low-temperature phases of VO2, revealing strain-tunable electronic properties and potential for piezotronic applications.

Contribution

It demonstrates the existence of piezoelectricity in VO2's low-temperature phases using piezo-response force microscopy, a novel finding in this material.

Findings

Piezoelectric coefficient of 11-12 pm/V in strained VO2 phases

Strain can distinguish and tune the M1 and M2 phases of VO2

First demonstration of piezoelectricity in VO2's low-temperature phases

Abstract

VO2 is well known for its dual phase transitions; electrical as well as structural, at a single temperature of 340K. The low temperature structural phases of VO2 are different from its high temperature counterpart by means of structural symmetry. The strain induced modification of the structural distortion in VO2 is studied in details. A ferroelectric type distortion is observed, and therefore, the piezoelectric effect in the low temperature phases of VO2 is investigated, for the first time, using piezo-response force microscopy. The electronic behavior of piezoelectric materials can be tuned with the application of mechanical strain and strain is the only factor to separate the two low-temperature phases, namely, M1 and M2 in the phase diagram of VO2. The piezo-electric coefficient in the strained phase of VO2 was found as 11-12 pm/V making it eligible for piezotronic applications.