Published

  (Laboratory for Materials and Structures / Dr. Sergey Nikolaev)

“Tunable vertical ferroelectricity and domain walls by interlayer sliding in β-ZrI₂”

npj Computational Materials  (DOI: 110.1038/s41524-021-00648-9)

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<Abstract>
Vertical ferroelectricity where a net dipole moment appears as a result of in-plane ionic displacements has gained enormous attention following its discovery in transition metal dichalcogenides. Based on first-principles calculations, we report on the evidence of robust vertical ferroelectricity upon interlayer sliding in layered semiconducting β-ZrI₂, a sister material of polar semimetals MoTe₂ and WTe₂. The microscopic origin of ferroelectricity in ZrI₂ is attributed to asymmetric shifts of electronic charges within a trilayer, revealing a subtle interplay of rigid sliding displacements and charge redistribution down to ultrathin thicknesses. We further investigate the variety of ferroelectric domain boundaries and predict a stable charged domain wall with a quasi-two-dimensional electron gas and a high built-in electric field that can increase electron mobility and electromechanical response in multifunctional devices. Semiconducting behaviour and a small switching barrier of ZrI₂ hold promise for various ferroelectric applications, and our results provide important insights for further development of slidetronics ferroelectricity.