Blanca-Romero, Ariadna; Pentcheva, Rossitza (2011): Confinement-induced metal-to-insulator transition in strained LaNiO3/LaAlO3 superlattices. In: Physical Review B, Vol. 84, Nr. 19
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Using density functional theory calculations including a Hubbard U termwe explore the effect of strain and confinement on the electronic groundstate of superlattices containing the band insulator LaAlO3 and thecorrelated metal LaNiO3. Besides a suppression of holes at the apicaloxygen, a central feature is the asymmetric response to strain in singleunit cell superlattices: For tensile strain a band gap opens due tocharge disproportionation at the Ni sites with two distinct magneticmoments of 1.45 mu(B) and 0.71 mu(B). Under compressive stain, chargedisproportionation is nearly quenched and the band gap collapses due tooverlap of d(3z2-r2) bands through a semimetallic state. This asymmetryin the electronic behavior is associated with the difference inoctahedral distortions and rotations under tensile and compressivestrain. The ligand hole density and the metallic state are quicklyrestored with increasing thickness of the (LaAlO3)(n)/(LaNiO3)(n)