IBM Almaden Research Center, San Jose, CA 95120, USA.
Science. 2013 Mar 22;339(6126):1402-5. doi: 10.1126/science.1230512.
Electrolyte gating with ionic liquids is a powerful tool for inducing novel conducting phases in correlated insulators. An archetypal correlated material is vanadium dioxide (VO(2)), which is insulating only at temperatures below a characteristic phase transition temperature. We show that electrolyte gating of epitaxial thin films of VO(2) suppresses the metal-to-insulator transition and stabilizes the metallic phase to temperatures below 5 kelvin, even after the ionic liquid is completely removed. We found that electrolyte gating of VO(2) leads not to electrostatically induced carriers but instead to the electric field-induced creation of oxygen vacancies, with consequent migration of oxygen from the oxide film into the ionic liquid. This mechanism should be taken into account in the interpretation of ionic liquid gating experiments.
离子液体电解质门控是诱导关联绝缘体中出现新型导相的有力工具。典型的关联材料是二氧化钒（VO2），其仅在低于特征相变温度的温度下为绝缘状态。我们表明，通过对 VO2 的外延薄膜进行电解质门控，可以抑制金属-绝缘体转变，并在完全除去离子液体后，将金属相稳定到 5 开尔文以下的温度。我们发现，VO2 的电解质门控不是导致静电诱导载流子，而是导致电场诱导氧空位的产生，从而导致氧从氧化物膜迁移到离子液体中。在解释离子液体门控实验时，应考虑这种机制。
