期刊
PHYSICAL REVIEW B
卷 92, 期 8, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevB.92.085201
关键词
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资金
- NSF MRSEC Program [DMR-1121053]
- International Center for Materials Research (ICMR)
- NSF-IMI Program [DMR08-43934]
- Australian Research Council (ARC)
- ARC
- ONR [N00014-12-1-0976]
- NSF [ACI-1053575]
- Direct For Mathematical & Physical Scien
- Division Of Materials Research [0843934] Funding Source: National Science Foundation
Using hybrid density functional calculations, we study the electronic and structural properties of SrZrO3 and ordered Sr(Ti,Zr)O-3 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 SrTixZr1-xO3 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 x 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 3d(xy) orbitals. The lifting of the t(2g) 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.
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