Electrical measurements of a VO2 thin film under high pressure of 25 GPa generated by a load-controllable point-contact structure

Utilizing a load-controllable point-contact structure with a steel probe as a high-pressure generator, pressure effects on electrical properties were investigated on a VO2 thin film grown on a metallic Ti substrate. Through comparisons at 300 and 348 K of the resistance of a VO2/Ti sample under the probe and the resistivity of VO2 under hydrostatic pressure that was previously reported, the pressure corresponding to a probe load of 25 gf was estimated to be as high as 25.5 GPa, and the contact area was supposed to be unchanged up to this probe load. The combination of a point-contact system and a film deposited on a metal substrate has enabled the observation of a switching induced by an electric field perpendicular to the plane of a VO2 film. The transition voltage was drastically suppressed by an application of about 10 GPa with the probe. The load-controllable point-contact system was demonstrated to be a simple but usable tool for studying the physical properties of thin films under high pressures.