Ordering and multiple phase transitions in ultra-thin nickelate   superlattices
  We interpret via advanced ab initio calculations the multiple phase transitions observed recently in ultra-thin LaNiO$_{3}$/LaAlO$_{3}$ superlattices. The ground state is insulating, charge-ordered, and antiferromagnetic due to concurrent structural distortion and weak valency disproportionation. We infer distinct transitions at 40 K and 150 K, respectively, from antiferromagnetic order to moment disorder, and from structurally-dimerized insulator to an undistorted metallic Pauli paramagnet (exhibiting a cuprate-like Fermi surface). The results are in satisfactory agreement with experiment. 
Danilo Puggioni, Alessio Filippetti, Vincenzo Fiorentini
cond-mat.mtrl-sci