Structural and electronic properties of SrZrO3 and Sr(Ti,Zr)O3 alloys
Date
2015-08-11
Journal Title
Journal ISSN
Volume Title
Publisher
American Physical Society
Abstract
Using hybrid density functional calculations, we study the electronic and structural properties of SrZrO3
and ordered Sr(Ti,Zr)O3 alloys. Calculations were performed for the ground-state orthorhombic (Pnma) and
high-temperature cubic (Pm3m) phases of SrZrO3. The variation of the lattice parameters and band gaps with Ti
addition was studied using ordered SrTix Zr1−x O3 structures with x = 0, 0.25, 0.5, 0.75, and 1. As Ti is added
to SrZrO3, the lattice parameter is reduced and closely follows Vegard’s law. On the other hand, the band gap
shows a large bowing and is highly sensitive to the Ti distribution. For x = 0.5, we find that arranging the Ti
and Zr atoms into a 1 × 1 SrZrO3/SrTiO3 superlattice along the [001] direction leads to interesting properties,
including a highly dispersive single band at the conduction-band minimum (CBM), which is absent in both parent
compounds, and a band gap close to that of pure SrTiO3. These features are explained by the splitting of the lowest
three conduction-band states due to the reduced symmetry of the superlattice, lowering the band originating from
the in-plane Ti 3dxy orbitals. The lifting of the t2g orbital degeneracy around the CBM suppresses scattering due
to electron-phonon interactions. Our results demonstrate how short-period SrZrO3/SrTiO3 superlattices could be
exploited to engineer the band structure and improve carrier mobility compared to bulk SrTiO3.
Description
Publisher's PDF
Keywords
Citation
Weston, L., et al. "Structural and electronic properties of SrZrO 3 and Sr (Ti, Zr) O 3 alloys." Physical Review B 92.8 (2015): 085201.