Nonlinear Optical Response in Layer‐Stacked Gallenene with Ferroelectric Polarization
Abstract
Abstract Polar metals are very rare and challenging to realize due to the incompatibility of ferroelectricity and metallicity. Mobile electrons in polar metals effectively screen the static electric field and dipoles. Recent studies show that 2D van der Waals metals without an inversion center can have polar order due to specific layer stacking. However, room temperature reversible ferroelectricity and nonlinear second harmonic generation in non‐centrosymmetric polar metals remain unrealized. Here, the experimental realization of AB‐stacked gallenene (a100) nanocrystals with a room temperature ferroelectric polarization in a liquid gallium environment is reported. Using first‐principles calculations, the origin of spontaneous polarization (Ps) due to a broken symmetry in multilayer gallenene structures, resulting in P1 (space group) and C1 (point group) symmetry is explained. The reversible polarization switching is characterized using piezoresponse force microscopy. This results demonstrate the reversible nonlinear optical response of the AB‐stacked gallenene crystal through second harmonic generation (SHG) microscopy. The intensities of SHG signals are controlled via angular rotations and thermal heating, which indicate a phase transition at high temperatures. Furthermore, electrical perturbation enables the tunability of SHG intensity. Bipolar resistive switching is demonstrated in a two‐terminal device. These findings open avenues for advancements in 2D ferroelectricity, piezoelectricity, and topological superconductivity.
Article Details
Authors (18)
Muhammad Yunusa
Physical Intelligence Department Max Planck Institute for Intelligent Systems 70569 Stuttgart Germany
Andrew K. Schulz
Max Planck Institute for Intelligent Systems 70569 Stuttgart Germany
Tim Parker
Institute of Physical and Theoretical Chemistry Eberhard Karls University of Tübingen Auf der Morgenstelle 15 72076 Tübingen Germany
Felix Schneider
Kenan Elibol
Max Planck Institute for Solid State Research 70569 Stuttgart Germany
Marius Predel
Faculty of Physics University of Vienna Boltzmanngasse 5 Vienna 1090 Austria
Jana Dzíbelová
Faculty of Physics University of Vienna Boltzmanngasse 5 Vienna 1090 Austria
Michel Rebmann
Institute of Physical and Theoretical Chemistry Eberhard Karls University of Tübingen Auf der Morgenstelle 15 72076 Tübingen Germany
Taylan Gorkan
UNAM‐National Nanotechnology Research Center and Institute of Materials Science and Nanotechnology Bilkent University Ankara 06800 Turkey
Jiahao Ye
Jin‐Chong Tan
Multifunctional Materials and Composites (MMC) Laboratory Department of Engineering Science University of Oxford Oxford OX1 3PJ UK
Wenbin Kang
Peter A. van Aken
Max Planck Institute for Solid State Research, Heisenbergstr. 1, Stuttgart 70569, Germany
Alfred J. Meixner
Institute of Physical and Theoretical Chemistry Eberhard Karls University of Tübingen Auf der Morgenstelle 15 72076 Tübingen Germany
Engin Durgun
UNAM‐National Nanotechnology Research Center and Institute of Materials Science and Nanotechnology Bilkent University Ankara 06800 Turkey
Jani Kotakoski
Faculty of Physics University of Vienna Boltzmanngasse 5 Vienna 1090 Austria
Dai Zhang
Metin Sitti