Theoretical designs of low-barrier ferroelectricity

Abstract

Ferroelectrics with electrically switchable spontaneous polarizations can be used for information storage, where a low switching barrier is favorable to reduce the energy cost and enhance the speed for data writing. Meanwhile their robustness at working temperature should be ensured, which is a challenge for the designs of low-barrier ferroelectrics. Here we review several types of ferroelectric mechanisms that may render both low switching barriers and room-temperature robustness, which have been theoretically proposed in previous studies. (1) The prediction of sliding ferroelectricity with ultralow switching barriers has been experimentally confirmed in a series of van der Waals layers, which may enable convenient electrical control of various physical properties in 2D materials, like magnetic, photovoltaic, valleytronic and topological properties. (2) Hydrogen-bonded ferroelectricity spontaneously formed by head-to-tail chains can be switched by proton-transfer crossing a low barrier, and a mechanism of ultra-high piezoelectricity utilizing the specific features of hydrogen bonding has been proposed. (3) High-ionicity ferroelectricity induced by covalent-like ionic bondings may entail high polarizations and low barriers during switching, which is attributed to the features of long-range Coulomb interaction, and the long ion-displacements crossing unitcell may give rise to unconventional ferroelectricity with quantized polarizations even in crystals of non-ferroelectric point groups. Those low-barrier ferroelectric mechanisms may bring in both new physics and technological advances, which are to be further explored.

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