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Confinement-induced metal-to-insulator transition in strained LaNiO_{3}/LaAlO_{3} superlattices

Physical Review B 84(19): 195450

Autoren/Herausgeber: Blanca-Romero A
Pentcheva R
Erschienen: 2011
Using density functional theory calculations including a Hubbard U term we explore the effect of strain and confinement on the electronic ground state of superlattices containing the band insulator LaAlO3 and the correlated metal LaNiO3. Besides a suppression of holes at the apical oxygen, a central feature is the asymmetric response to strain in single unit cell superlattices: For tensile strain a band gap opens due to charge disproportionation at the Ni sites with two distinct magnetic moments of 1.45μB and 0.71μB. Under compressive stain, charge disproportionation is nearly quenched and the band gap collapses due to overlap of d3z2−r2 bands through a semimetallic state. This asymmetry in the electronic behavior is associated with the difference in octahedral distortions and rotations under tensile and compressive strain. The ligand hole density and the metallic state are quickly restored with increasing thickness of the (LaAlO3)n/(LaNiO3)n superlattice from n=1 to n=3.

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