Discovery of robust interlocked ferroelectricity in 2D AgCrSe2via chemical vapor deposition

Abstract

Ferroelectricity in two-dimensional (2D) materials at room temperature has attracted considerable interest due to their significant potential in electrical applications. However, studies on the precisely controlled synthesis of 2D ferroelectric materials remain limited so far. Here in, this work reports a novel large-area 2D ferroelectric material AgCrSe₂ synthesized via CVD method. Nonlinear optical measurement demonstrate that AgCrSe₂ nanoflakes grown at 880 °C exhibit strong second harmonic generation (SHG) responses. Atomic-scale characterization reveals that the displacement of Ag sublattices generates switchable dipoles, inducing both in-plane and out-of-plane ferroelectricity. This dipole alignment, verified by piezoresponse force microscopy (PFM), exhibits a high piezoelectric effective d₃₃ (0.48 pm V⁻¹) and reversible switching via electric-field-driven Ag⁺ migration across an energy barrier of 0.34 eV. Furthermore, ferroelectric devices with an ultrathin 9.4 nm active layer exhibit a robust remanent polarization of 1.5 μC cm⁻², a coercive field of 5 kV cm⁻¹, and stable nonvolatile resistive states with on/off ratios exceeding 10². This study expands the selection of 2D ferroelectric materials and provides new opportunities for the development of ferroelectric devices.