title: Indications of an electronic phase transition in two-dimensional superconducting YBa2Cu3O(7-x) thin films induced by electrostatic doping.
abstract: We successfully tuned an underdoped ultrathin YBa2Cu3O(7-x) film into the overdoped regime by means of electrostatic doping using an ionic liquid as a dielectric material. This process proved to be reversible. Transport measurements showed a series of anomalous features compared to chemically doped bulk samples and a different two-step doping mechanism for electrostatic doping was revealed. The normal resistance increased with carrier concentration on the overdoped side and the high temperature (180 K) Hall number peaked at a doping level of p∼0.15. These anomalous behaviors suggest that there is an electronic phase transition in the Fermi surface around the optimal doping level.
authors.affiliation: School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Xiang
authors.initials: X
authors.lastname: Leng
authors.forename: Javier
authors.initials: J
authors.lastname: Garcia-Barriocanal
authors.forename: Boyi
authors.initials: B
authors.lastname: Yang
authors.forename: Yeonbae
authors.initials: Y
authors.lastname: Lee
authors.forename: J
authors.initials: J
authors.lastname: Kinney
authors.forename: A M
authors.initials: AM
authors.lastname: Goldman