title: Gate-tunable phase transitions in thin flakes of 1T-TaS2.
abstract: The ability to tune material properties using gating by electric fields is at the heart of modern electronic technology. It is also a driving force behind recent advances in two-dimensional systems, such as the observation of gate electric-field-induced superconductivity and metal-insulator transitions. Here, we describe an ionic field-effect transistor (termed an iFET), in which gate-controlled Li ion intercalation modulates the material properties of layered crystals of 1T-TaS2. The strong charge doping induced by the tunable ion intercalation alters the energetics of various charge-ordered states in 1T-TaS2 and produces a series of phase transitions in thin-flake samples with reduced dimensionality. We find that the charge-density wave states in 1T-TaS2 collapse in the two-dimensional limit at critical thicknesses. Meanwhile, at low temperatures, the ionic gating induces multiple phase transitions from Mott-insulator to metal in 1T-TaS2 thin flakes, with five orders of magnitude modulation in resistance, and superconductivity emerges in a textured charge-density wave state induced by ionic gating. Our method of gate-controlled intercalation opens up possibilities in searching for novel states of matter in the extreme charge-carrier-concentration limit.
authors.affiliation: 1] State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China [2] Collaborative Innovation Center of Advanced Microstructures, 22 Hankou Road, Gulou, Nanjing 210093, China.
authors.forename: Yijun
authors.initials: Y
authors.lastname: Yu
authors.affiliation: 1] State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China [2] Collaborative Innovation Center of Advanced Microstructures, 22 Hankou Road, Gulou, Nanjing 210093, China.
authors.forename: Fangyuan
authors.initials: F
authors.lastname: Yang
authors.affiliation: 1] Collaborative Innovation Center of Advanced Microstructures, 22 Hankou Road, Gulou, Nanjing 210093, China [2] Hefei National Laboratory for Physical Science at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China [3] Key Laboratory of Strongly Coupled Quantum Matter Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: Xiu Fang
authors.initials: XF
authors.lastname: Lu
authors.affiliation: 1] State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China [2] Collaborative Innovation Center of Advanced Microstructures, 22 Hankou Road, Gulou, Nanjing 210093, China [3] Hefei National Laboratory for Physical Science at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: Ya Jun
authors.initials: YJ
authors.lastname: Yan
authors.affiliation: Laboratory for Pohang Emergent Materials and Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea.
authors.forename: Yong-Heum
authors.initials: YH
authors.lastname: Cho
authors.affiliation: 1] State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China [2] Collaborative Innovation Center of Advanced Microstructures, 22 Hankou Road, Gulou, Nanjing 210093, China.
authors.forename: Liguo
authors.initials: L
authors.lastname: Ma
authors.affiliation: 1] State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China [2] Collaborative Innovation Center of Advanced Microstructures, 22 Hankou Road, Gulou, Nanjing 210093, China.
authors.forename: Xiaohai
authors.initials: X
authors.lastname: Niu
authors.affiliation: Korea Institute for Advanced Study, Hoegiro 87, Dongdaemun-gu, Seoul, Korea.
authors.forename: Sejoong
authors.initials: S
authors.lastname: Kim
authors.affiliation: Korea Institute for Advanced Study, Hoegiro 87, Dongdaemun-gu, Seoul, Korea.
authors.forename: Young-Woo
authors.initials: YW
authors.lastname: Son
authors.affiliation: 1] State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China [2] Collaborative Innovation Center of Advanced Microstructures, 22 Hankou Road, Gulou, Nanjing 210093, China.
authors.forename: Donglai
authors.initials: D
authors.lastname: Feng
authors.affiliation: 1] State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China [2] Collaborative Innovation Center of Advanced Microstructures, 22 Hankou Road, Gulou, Nanjing 210093, China.
authors.forename: Shiyan
authors.initials: S
authors.lastname: Li
authors.affiliation: 1] Laboratory for Pohang Emergent Materials and Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea [2] Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA.
authors.forename: Sang-Wook
authors.initials: SW
authors.lastname: Cheong
authors.affiliation: 1] Collaborative Innovation Center of Advanced Microstructures, 22 Hankou Road, Gulou, Nanjing 210093, China [2] Hefei National Laboratory for Physical Science at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China [3] Key Laboratory of Strongly Coupled Quantum Matter Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: Xian Hui
authors.initials: XH
authors.lastname: Chen
authors.affiliation: 1] State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China [2] Collaborative Innovation Center of Advanced Microstructures, 22 Hankou Road, Gulou, Nanjing 210093, China.
authors.forename: Yuanbo
authors.initials: Y
authors.lastname: Zhang