R&D: Ferroelectric 2D Ice Under Graphene Confinement

Nature Communications has published an article written by Hao-Ting Chin, Institute for Atomic and Molecular Science, Academia Sinica, Taipei, 10617, Taiwan, International Graduate Program of Molecular Science and Technology, National Taiwan University, Taipei, 10617, Taiwan, and Molecular Science and Technology Program, Taiwan International Graduate Program, Academia Sinica, Taipei, 10617, Taiwan, Jiri Klimes, Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University, Prague, 121 16, Czech Republic, I-Fan Hu, Institute for Atomic and Molecular Science, Academia Sinica, Taipei, 10617, Taiwan, and Department of Physics, National Taiwan University, Taipei, 10617, Taiwan, Ding-Rui Chen, Institute for Atomic and Molecular Science, Academia Sinica, Taipei, 10617, Taiwan, International Graduate Program of Molecular Science and Technology, National Taiwan University, Taipei, 10617, Taiwan, and Molecular Science and Technology Program, Taiwan International Graduate Program, Academia Sinica, Taipei, 10617, Taiwan, Hai-Thai Nguyen, Department of Physics, National Taiwan University, Taipei, 10617, Taiwan, Department of Materials Science and Engineering, National Cheng Kung University, Tainan, 70101, Taiwan, Ting-Wei Chen, Shao-Wei Ma, Graduate Institute of Opto-Mechatronics, National Chung Cheng University, Chiayi, 62102, Taiwan, Mario Hofmann, Chi-Te Liang, Department of Physics, National Taiwan University, Taipei, 10617, Taiwan, and Ya-Ping Hsieh, Institute for Atomic and Molecular Science, Academia Sinica, Taipei, 10617, Taiwan.

Abstract: “We here report on the direct observation of ferroelectric properties of water ice in its 2D phase. Upon nanoelectromechanical confinement between two graphene layers, water forms a 2D ice phase at room temperature that exhibits a strong and permanent dipole which depends on the previously applied field, representing clear evidence for ferroelectric ordering. Characterization of this permanent polarization with respect to varying water partial pressure and temperature reveals the importance of forming a monolayer of 2D ice for ferroelectric ordering which agrees with ab-initio and molecular dynamics simulations conducted. The observed robust ferroelectric properties of 2D ice enable novel nanoelectromechanical devices that exhibit memristive properties. A unique bipolar mechanical switching behavior is observed where previous charging history controls the transition voltage between low-resistance and high-resistance state. This advance enables the realization of rugged, non-volatile, mechanical memory exhibiting switching ratios of 106, 4 bit storage capabilities and no degradation after 10,000 switching cycles.“