Strain modulation of TaO4 planarity in tantalates ultrathin films: surface states engineering

Author(s)

Portugal, Guilherme Ribeiro ^[1] ; Arantes, Jeverson Teodoro ^[1]

Affiliation

^[1] Fed Univ ABC UFABC, Ctr Engn Modeling & Appl Social Sci CECS, Santo Andre, SP - Brazil

• Document type: Journal article
• Source: SCIENTIFIC REPORTS; v. 10, n. 1 MAY 8 2020.
• Web of Science Citations: 0

Abstract

Ultrathin films of perovskites have attracted considerable attention once they fit in numerous applications. Over the years, controlling and tuning their properties have been attainable when biaxial strain is applied. Through ab initio DFT calculations, (110) ultrathin (Na,K)TaO3 films were submitted to biaxial tensile and compressive strain. Intrinsically, surface Ta shallow states emerge into the bandgap since the (110) cleavage breaks its octahedral symmetry to create TaO4 units. Removal of ligands along the x-y plane stabilizes d(x)(-y)(2)(2) orbitals, which decrease in energy due to lower electrostatic repulsion. Such stabilization is maximized when biaxial tensile increases the TaO4 planarity towards a square planar symmetry. Accordingly, the corresponding electronic levels move further into the bandgap. Conversely, compressive biaxial strain intensifies electrostatic repulsion, closing the TaO4 tetrahedra, and surface states move to higher energy zones. The reported strain-driven modulation might be applied in different applications, as photocatalysis, ferroelectricity, and spintronics. (AU)

• FAPESP's process: 17/02317-2 - Interfaces in materials: electronic, magnetic, structural and transport properties
• Grantee: Adalberto Fazzio
• Support Opportunities: Research Projects - Thematic Grants