Room-temperature electric field-induced out-of-plane ferroelectric polarization in strain-free freestanding 2D SrTiO3 membranes
Yueying Zhang,
Jiaming Li,
Ke Yang,
Fangyuan Zheng,
Yuqing Zhou,
Yuguo Zhang,
Yupeng Hui,
Yue-Qi Wang,
Jiang Zhu,
Jincheng Zhang,
Yue Hao,
Ming Yang,
Tao Li,
Jiong Zhao,
Haijiao Harsan Ma
Affiliations
Yueying Zhang
Low Dimensional Quantum Physics & Device Group, School of Microelectronics, Xidian University, 2 South Taibai Road, Xi’an 710071, China
Jiaming Li
Department of Materials Science and Engineering, Center for Spintronics and Quantum Systems, State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, China
Ke Yang
Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China
Fangyuan Zheng
Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China
Yuqing Zhou
Department of Materials Science and Engineering, Center for Spintronics and Quantum Systems, State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, China
Yuguo Zhang
Low Dimensional Quantum Physics & Device Group, School of Microelectronics, Xidian University, 2 South Taibai Road, Xi’an 710071, China
Yupeng Hui
Low Dimensional Quantum Physics & Device Group, School of Microelectronics, Xidian University, 2 South Taibai Road, Xi’an 710071, China
Yue-Qi Wang
Low Dimensional Quantum Physics & Device Group, School of Microelectronics, Xidian University, 2 South Taibai Road, Xi’an 710071, China
Jiang Zhu
Low Dimensional Quantum Physics & Device Group, School of Microelectronics, Xidian University, 2 South Taibai Road, Xi’an 710071, China
Jincheng Zhang
Low Dimensional Quantum Physics & Device Group, School of Microelectronics, Xidian University, 2 South Taibai Road, Xi’an 710071, China
Yue Hao
Low Dimensional Quantum Physics & Device Group, School of Microelectronics, Xidian University, 2 South Taibai Road, Xi’an 710071, China
Ming Yang
Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China
Tao Li
Department of Materials Science and Engineering, Center for Spintronics and Quantum Systems, State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, China
Jiong Zhao
Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China
Haijiao Harsan Ma
Low Dimensional Quantum Physics & Device Group, School of Microelectronics, Xidian University, 2 South Taibai Road, Xi’an 710071, China
SrTiO3 (STO), a room-temperature paraelectric material in bulk form, has been a rich playground for emergent phenomena for decades. As an emerging material, great attention has been paid to freestanding 2D STO thin films. Recently, the room-temperature ferroelectricity has been unveiled in strained STO thin films; however, it remains an open question whether the strain-free freestanding 2D STO thin film is room-temperature ferroelectric or not. Here, we report the electric field-induced out-of-plane ferroelectric polarization in large-scale, freestanding, and strain-free 2D STO membranes at room temperature. High-resolution piezoresponse force microscopy measurements show that polarization in freestanding strain-free STO membranes can be switched by electric field and persist for an hour. The first-principles calculations suggest that the intrinsic defects such as oxygen vacancies could be linked to the observed spontaneous out-of-plane polarization in 2D STO membranes, which could be further enhanced by external electric field due to the induced symmetry breaking. Our work reports the unprecedented room-temperature ferroelectric polarization in strain-free freestanding 2D STO membranes, unlocking the great potential of freestanding 2D STO for the applications in novel electronic and logic-in-memory devices.
