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Yin R, Ma L, Wang Z, Ma C, Chen X, Wang B. Reversible Superconductor-Insulator Transition in (Li, Fe)OHFeSe Flakes Visualized by Gate-Tunable Scanning Tunneling Spectroscopy. ACS Nano 2020; 14:7513-7519. [PMID: 32510920 DOI: 10.1021/acsnano.0c03289] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Electric field control of charge carrier density provides a key in situ technology to continuously tune the ground states and map out the phase diagram of correlated electron systems in one device. This technique is highly expected to be combined with the modern state-of-the art spectroscopic probes, such as angle-resolved photoemission spectroscopy and scanning tunneling microscopy/spectroscopy (STM/S), to efficiently address these states and the underlying physics. However, it is extremely difficult and not successful so far, mainly because the fabrication process of such devices makes them prohibitive for surface probes. Here, by using a solid Li-ion conductor (SIC) as gate dielectric, we have successfully developed gate-tunable STM/S and visualized the superconductor-insulator transition (SIT) in a thin flake of single crystal (Li, Fe)OHFeSe at the nanoscale. The gate-controlled Li-ion injection first enhances the superconductivity and then drives the flake into an inhomogeneous insulating state, where superconductivity is totally suppressed. This process can be reversed by applying an opposite gate voltage. Importantly, the atomically resolved images allow us to identify the critical role that the injected Li ions play in the tuning process. Our results not only provide clear evidence of the microscopic mechanism of the tunable superconductivity and SIT in the SIC-based (Li, Fe)OHFeSe devices, but also establish SIC-gating STM as a powerful tool for investigating the complicated phase diagram of correlated electron system spectroscopically in a single sample with the field-effect approach.
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Affiliation(s)
- Ruoting Yin
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Likuan Ma
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
- Department of Physics, and CAS Key Laboratory of Strongly Coupled Quantum Matter Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Zhenyu Wang
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
- Department of Physics, and CAS Key Laboratory of Strongly Coupled Quantum Matter Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Chuanxu Ma
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Xianhui Chen
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
- Department of Physics, and CAS Key Laboratory of Strongly Coupled Quantum Matter Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
- CAS Center for Excellence in Quantum Information and Quantum Physics, Hefei, Anhui 230026, China
| | - Bing Wang
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
- CAS Center for Excellence in Quantum Information and Quantum Physics, Hefei, Anhui 230026, China
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Liao M, Zhu Y, Zhang J, Zhong R, Schneeloch J, Gu G, Jiang K, Zhang D, Ma X, Xue QK. Superconductor-Insulator Transitions in Exfoliated Bi 2Sr 2CaCu 2O 8+δ Flakes. Nano Lett 2018; 18:5660-5665. [PMID: 30111116 DOI: 10.1021/acs.nanolett.8b02183] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We realize superconductor-insulator transitions (SIT) in mechanically exfoliated Bi2Sr2CaCu2O8+δ (BSCCO) flakes and address simultaneously their transport properties as well as the evolution of density of states. Back-gating via the solid ion conductor (SIC) engenders a SIT in BSCCO due to the modulation of carrier density by intercalated lithium ions. Scaling analysis indicates that the SIT follows the theoretical description of a two-dimensional quantum phase transition (2D-QPT). We further carry out tunneling spectroscopy in graphite(G)/BSCCO heterojunctions. We observe V-shaped gaps in the critical regime of the SIT. The density of states in BSCCO gets symmetrically suppressed by further going into the insulating regime. Our technique of combining solid state gating with tunneling spectroscopy can be easily applied to the study of other two-dimensional materials.
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Affiliation(s)
- Menghan Liao
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics , Tsinghua University , Beijing , 100084 , China
| | - Yuying Zhu
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics , Tsinghua University , Beijing , 100084 , China
| | - Jin Zhang
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics , Tsinghua University , Beijing , 100084 , China
| | - Ruidan Zhong
- Condensed Matter Physics and Materials Science Department , Brookhaven National Laboratory , Upton , New York 11973 , United States
| | - John Schneeloch
- Condensed Matter Physics and Materials Science Department , Brookhaven National Laboratory , Upton , New York 11973 , United States
- Department of Physics and Astronomy , Stony Brook University , Stony Brook , New York 11794 , United States
| | - Genda Gu
- Condensed Matter Physics and Materials Science Department , Brookhaven National Laboratory , Upton , New York 11973 , United States
| | - Kaili Jiang
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics , Tsinghua University , Beijing , 100084 , China
- Tsinghua-Foxconn Nanotechnology Research Center , Tsinghua University , Beijing , 100084 , China
- Collaborative Innovation Center of Quantum Matter , Beijing 100084 , China
| | - Ding Zhang
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics , Tsinghua University , Beijing , 100084 , China
- Collaborative Innovation Center of Quantum Matter , Beijing 100084 , China
| | - Xucun Ma
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics , Tsinghua University , Beijing , 100084 , China
- Collaborative Innovation Center of Quantum Matter , Beijing 100084 , China
| | - Qi-Kun Xue
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics , Tsinghua University , Beijing , 100084 , China
- Collaborative Innovation Center of Quantum Matter , Beijing 100084 , China
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