Recent advances in theoretical investigations of sliding ferroelectricity in layered and van der Waals two-dimensional materials

Abstract With the growing demand for faster, more efficient, and non-volatile memory technologies, ferroelectric materials have become integral to modern electronics. Sliding ferroelectricity, arising from the relative motion of van der Waals bonded layers, is more prevalent in layered and two-dimensional (2D) materials than conventional ferroelectricity. This review explores theoretically proposed sliding ferroelectric materials, discussing its origin in charge transfer and orbital distortion. Replacing layers with molecular systems offers a promising avenue to enhance storage density significantly. The impact of external stimuli, such as strain, pressure, and electric fields, is analyzed alongside laser-induced polarization switching and its association with “dynamical multiferroicity”. Across-layer sliding ferroelectricity in multilayer systems arising due to next-to-adjacent neighbor permits sliding electric polarization in single-element multilayer systems, thus increasing the range of materials exhibiting sliding ferroelectricity. The recently proposed ferroelectric switching in moiré superlattices in multilayer systems increases the possibility of utilizing more sliding ferroelectricity in device applications. The review highlights the dependence of spin textures on ferroelectric polarization and layer polarization, which has potential applications in spintronics. The coupling of ferroic orders, such as ferroelasticity and (anti)ferromagnetism, presents multistate switching opportunities and the ability to tune one property by manipulating another. A discussion of general theory underscores the importance of material symmetries, such as mirror, inversion, and rotational symmetries, in determining the existence of sliding ferroelectricity. Broken PT symmetry allows the existence of an altermagnetic phase and anomalous Hall effect and magneto-optic Kerr effect in ferroelectric antiferromagnets. Continuum electromechanics and thermodynamic analysis reveal a first-order ferroelectric-to-paraelectric phase transition. Despite its low energy switching barrier, the robust nature of sliding ferroelectric polarization is attributed to the higher intralayer stiffness of 2D materials.