Strain effects on the electronic properties in δ -doped oxide superlattices

Journal Article · Sat Feb 07 00:00:00 EST 2015 · Journal of Physics. D, Applied Physics

DOI:https://doi.org/10.1088/0022-3727/48/8/085303· OSTI ID:1185729

You, Jeong Ho ^[1]; Lee, Jun Hee ^[2]; Okamoto, Satoshi ^[2]; Cooper, Valentino ^[2]; Lee, Ho Nyung ^[2]

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1. Southern Methodist Univ., Dallas, TX (United States). Dept. of Mechanical Engineering
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division

We investigated strain effects on the electronic properties of (LaTiO₃)₁/(SrTiO₃)N superlattices using density functional theory. Under biaxial in-plane strain within the range of -5% ≤ _ε// ≤ 5%, the d_xy orbital electrons are highly localized at the interfaces whereas the d_yz and d_xz orbital electrons are more distributed in the SrTiO₃ (STO) spacer layers. For STO thickness N ≥ 3 unit cells (u.c.), the d_xy orbital electrons form two-dimensional (2D) electron gases (2DEGs). The quantized energy levels of the 2DEG are insensitive to the STO spacer thickness, but are strongly dependent on the applied biaxial in-plane strain. As the in-plane strain changes from compressive to tensile, the quantized energy levels of the dxy orbitals decrease thereby creating more states with 2D character. In contrast to the d_xy orbital, the d_yz and dxz orbitals always have three-dimensional (3D) transport characteristics and their energy levels increase as the strain changes from compressive to tensile. In conclusion, since the charge densities in the d_xy orbital and the d_yz and d_xz orbitals respond to biaxial in-plane strain in an opposite way, the transport dimensionality of the majority carriers can be controlled between 2D and 3D by applying biaxial in-plane strain.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 1185729
• Journal Information: Journal of Physics. D, Applied Physics, Vol. 48, Issue 8; ISSN 0022-3727
• Publisher: IOP Publishing
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
oxide superlattice
LTO/STO heterostructure
electronic reconstruction