Novel Study of Strain-Induced Piezoelectricity in VO 2 .

VO 2 is well known for its dual-phase transitions, electrical and structural, at a single temperature of 340 K. The low-temperature structural phases of VO 2 are different from their high-temperature counterpart in terms of structural symmetry. The strain-induced modification of the structural distortion in VO 2 is studied in detail. A ferroelectric-type distortion is observed, and therefore, the piezoelectric effect in the low-temperature phases of VO 2 is investigated, for the first time, by piezoresponse force microscopy. Strain is one of the factors that can modify the electronic behavior of piezoelectric materials. At the same time, the two low-temperature phases of VO 2 (M1 and M2) can only be separated by the application of strain. The piezoelectric coefficient in the strained phase of VO 2 was found to be 11-12 pm/V, making it eligible for piezotronic applications.