Browsing by Author "Weston, L."
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Item Structural and electronic properties of SrZrO3 and Sr(Ti,Zr)O3 alloys(American Physical Society, 2015-08-11) Weston, L.; Janotti, Anderson; Cui, X. Y.; Himmetoglu, B.; Stampfl, C.; Van de Walle, Chris G.; L. Weston, A. Janotti, X. Y. Cui, B. Himmetoglu, C. Stampfl, and C. G. Van de Walle; Janotti, AndersonUsing 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.