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Tunable correlated-electron phases in (111) LaAlO_(3)/SrTiO_(3) band insulator heterostructures

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Beltrán Finez, Juan Ignacio and Muñoz, M. Carmen (2017) Tunable correlated-electron phases in (111) LaAlO_(3)/SrTiO_(3) band insulator heterostructures. Physical Review B, 95 (24). ISSN ISSN: 2469-9950, ESSN: 2469-9969

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Official URL: http://dx.doi.org/10.1103/PhysRevB.95.245120


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Abstract

Density functional theory calculations reveal the existence of different correlated-electron ground states in (111)-oriented n-type LaAlO_(3)/SrTiO_(3) symmetric superlattices. They can be tuned by selecting the SrTiO3 thickness, and range from a trivial metal for thick SrTiO_(3) slabs to a Mott-type antiferromagnet in the ultrathin limit. An itinerant ferromagnet and a half-metal phase are also stable in the intermediate region. This remarkable property is a distinct characteristic of (111) perovskite heterostructures and originates from the combined effect of polar discontinuity at the interface, trigonal lattice symmetry, and quantum confinement. While the polar discontinuity promotes the filling of the empty d states of the SrTiO_(3) with one electron, the trigonal symmetry dictates that the wave function of the occupied bands spreads over the entire SrTiO3 slab. Thus, the electron density can be chosen by selecting the number of SrTiO_(3) layers. For high densities, symmetry breaking and on-site Coulomb interaction drive the occurrence of correlated-electron ground states. Our results show that low dimensionality can lead to unconventional behavior of oxide heterostructures formed by electronically fairly simple nonmagnetic band insulators, and can open perspectives for the use of LaAlO_(3)/SrTiO_(3) superlattices grown along the [111] direction to explore quantum phase transitions.


Item Type:Article
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© 2017 American Physical Society. This work has been supported by the Spanish Ministry of Economy and Competitiveness through MINECO/FEDER Grants No. MAT2015-66888-C3-1R and No. 3R. The use of computational resources of CESGA is acknowledged.

Uncontrolled Keywords:Augmented-wave method; Interfaces; Superconductivity; Ferromagnetism; Conductivity; Coexistence; Oxides; GAS.
Subjects:Sciences > Physics > Physics-Mathematical models
ID Code:44561
Deposited On:22 Nov 2017 12:27
Last Modified:10 Dec 2018 14:57

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