Ordering and multiple phase transitions in ultrathin nickelate superlattices

Puggioni D;FILIPPETTI, ALESSIO;FIORENTINI, VINCENZO

2012-01-01

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Abstract

We interpret via advanced ab initio calculations the multiple phase transitions observed recently in ultrathin LaNiO3/LaAlO3 superlattices. The ground state is insulating, weakly charge ordered, and antiferromagnetic due to concurrent structural distortion and weak valency disproportionation. We infer distinct transitions around 50 K and 110 K, respectively, from antiferromagnetic order to moment disorder, and from a structurally dimerized insulator to an undistorted metallic Pauli paramagnet (exhibiting a cupratelike Fermi surface). The results are in satisfactory agreement with experimental results.