FisMat2017 - Submission - View

Abstract's title: Optical properties of nickelate heterostructures
Submitting author: Paola Di Pietro
Affiliation: Elettra Sincrotrone Trieste
Affiliation Address: S.S. 14 km 163.5 in AREA Science Park, 34149, Basovizza,Trieste
Country: Italy
Oral presentation/Poster (Author's request): Oral presentation
Other authors and affiliations: P. Orgiani2, 2CNR-SPIN, UOS Salerno, Fisciano, Salerno I-84084, Italy M. Golalikhani3, L. Kasaei3, Qingyu Lei3, Xiaoxing Xi3, 3Physics Department, Temple University, Philadelphia, PA-19122, USA S. Lupi4, 4CNR-IOM and Dipartimento di Fisica, Università di Roma Sapienza, P.le Aldo Moro 2, I-00185 Roma, Italy and A. Perucchi1, 1Elettra-Sincrotrone Trieste, Area Science Park, I-34012 Trieste, Italy

Here we provide a description of the optical behavior of nickelate heterostructures, that have recently gained remarkable interest, particularly those based on LaNiO3 (LNO), the unique nickelate that does not exhibit antiferromagnetic phase. Thus one may think to control its ground state by tuning several parameters, like two-dimensionality, strain due to the substrate and doping. In particular we have addressed the optical behavior in different LNO heterostructures in order to understand how some of the above mentioned degrees of freedom make rise a metal to insulator transition (MIT) in these systems.Taking the cue from the case of (LaNiO3)n/(LaMnO3)superlattices, in which interfacial doping makes them a system that is not a pure combination of LNO and LMO, we have studied LaNiO3/LaAlO3 (LNO/LAO) heterostructures. The interest of these systems is that the tuning of the dimensionality is the cause of the suppression of the Fermi-liquid behaviour in the metallic LNO and the occurrence of a metal-to-insulator transition. In particular, the optical conductivity of the thin films well reproduces that of thick LNO, while the conductivity of the SL becomes insulating, confirming the MIT observed by transport measurements. Another example of the dimensionality tuning in nickelates heterostructures is the Lan+1NinO3n+1 Ruddlesden-Popper series (R-P series), in which the intercalation of the rock salt LaO with n layers of  the perovskite LaNiO3 provides an intrinsic tuning of the dimensionality of the LNO heterostructure itself, without physically changing the number of LNO unit cells. In particular, we found thatthe optical conductivity of larger n resembles that of the bulk metallic LNO, while for smaller n the system undergoes  a metal to insulator transition, perfectly recovering the LNO/LAO behaviour.