Electrocaloric effect of metal-insulator transition in VO2

Abstract

The electrocaloric effect was observed in association with an electric-field induced metal-insulator transition in VO2 using a calorimetric measurement under an applied voltage. For a VO2 plate with a 0.4 mm thickness located in the center of a capacitor-like structure, the metal-insulator transition was manipulated by applying a few volts. The occurrence of a transition in such a thick sample with relatively low voltage indicates that a surface charge accumulation mechanism is effective. The isothermal entropy change reached 94 J kg−1 K−1, while the adiabatic temperature change was calculated as −3.8 K under a voltage change of 0–3 V. The large entropy change is attributed to correlation of the complex freedom among spin, charge, and lattice.