Despite progress in HfO_(2)thin-film ferroelectrics,issues like high coercive fields persist,and the dynamics of twisted ferroelectricity remain largely unexplored.Here,we explore how sliding and twisting in bilayer H...Despite progress in HfO_(2)thin-film ferroelectrics,issues like high coercive fields persist,and the dynamics of twisted ferroelectricity remain largely unexplored.Here,we explore how sliding and twisting in bilayer HfO_(2)enables low barrier switching.Among 144 sliding configurations,two exhibit strong in-plane polarization(2360 pC/m)with a low switching barrier of 9.57 meV/f.u.Twisting generates polar textures associated with moirépatterns,which drive ferroelectricity via a soft zonecenter mode,as revealed by machine-learning-assisted first-principles calculations.The in-plane(out-of-plane)polarization values for HfO_(2)at twist angles of 21.79°,27.80°,and 46.83°are 430(5.82),367(2.20),and 1057(0.03)pC/m,respectively.For 21.79°and 27.80°twisting,switching barriers drop to 1.74 and 0.18 meV/f.u.,indicating superlubric-like transitions.Notably,the 46.83°twisted bilayer shows an almost barrier-free polar evolution(0.03 meV/f.u.),attributed to sharply enhanced zonecenter phonon linewidths.Our findings establish a moiré-engineered switching route for 2D ferroelectrics.展开更多
基金funded by the Science and Technology Commission of Shanghai Municipality(No.24CL2901702)We acknowledge the Supercomputer Center,Institute for Solid State Physics,the University of Tokyo(Project number 2024-Cb-0042).
文摘Despite progress in HfO_(2)thin-film ferroelectrics,issues like high coercive fields persist,and the dynamics of twisted ferroelectricity remain largely unexplored.Here,we explore how sliding and twisting in bilayer HfO_(2)enables low barrier switching.Among 144 sliding configurations,two exhibit strong in-plane polarization(2360 pC/m)with a low switching barrier of 9.57 meV/f.u.Twisting generates polar textures associated with moirépatterns,which drive ferroelectricity via a soft zonecenter mode,as revealed by machine-learning-assisted first-principles calculations.The in-plane(out-of-plane)polarization values for HfO_(2)at twist angles of 21.79°,27.80°,and 46.83°are 430(5.82),367(2.20),and 1057(0.03)pC/m,respectively.For 21.79°and 27.80°twisting,switching barriers drop to 1.74 and 0.18 meV/f.u.,indicating superlubric-like transitions.Notably,the 46.83°twisted bilayer shows an almost barrier-free polar evolution(0.03 meV/f.u.),attributed to sharply enhanced zonecenter phonon linewidths.Our findings establish a moiré-engineered switching route for 2D ferroelectrics.
