Macroscopic and microscopic polarization of CuInP2S6 crystals

Abstract

With the rapid beginning of graphene research, interest in layered van der Waals materials has grown significantly. Among them, the Phosphorous Trichalcogenides group, which possess unique physical properties, stands out. In the list of these crystals, we can meet ferroelectrics, antiferroelectrics, ferromagnetics, ionic conductors, semiconductors, dielectrics, and others. Of particular interest are CuInP2S6 crystals, which below the Curie temperature T < TC = 315K are ferrielectrics with spontaneous polarization PS = 3 μC/cm2 directed perpendicularly to the structural layers. The coercivity field of these crystals is 77 kV/cm. Moreover, unlike most ferroelectrics, the ferrielectric properties of CuInP2S6 crystals are preserved even at thicknesses of units of nanometers (for example, Sn2P2S6 crystals cease to exhibit ferroelectric properties at a size of less than 50 microns), which makes it very promising for use in modern electronics. It has already been used to create major electronic components such as diodes, transistors, ferroelectric transistors with negative capacitance, memory cells, and others.