Evidence of Mn-Ion Structural Displacements Correlated to Oxygen Vacancies in La0.7Sr0.3MnO3 Interfacial Dead Layers

Piu Rajak (1) , Daniel Knez (2) , Sandeep Kumar Chaluvadi (1) , Pasquale Orgiani (1) , Giorgio Rossi (1) , Laurence Méchin (3) , Regina Ciancio (1)

1 IOM - CNR Istituto Officina dei Materiali
2 TU Graz - Graz University of Technology [Graz]
3 Equipe Electronique - Laboratoire GREYC - UMR6072

Properties of half-metallic manganite thin films depend on the composition and structure in the atomic scale, and consequently, their potential functional behaviour can only be based on fine structure characterization. By combining advanced transmission electron microscopy methods, electron energy loss spectroscopy, density functional theory (DFT) calculations, and multislice image simulations, we obtained evidence of a 7 nm-thick interface layer in La0.7Sr0.3MnO3 (LSMO) thin films, compatible with the formation of well-known dead layers in manganites, with an elongated out-of-plane lattice parameter, and structural and electronic properties well distinguished from the bulk of the film. We observed, for the first time, a structural shift of Mn ions coupled with oxygen vacancies and a reduced Mn valence state within such layer. Understanding the correlation between oxygen vacancies, the Mn oxidation state, and Mn ions displacements is a prerequisite to engineer the magneto-transport properties of LSMO thin films.

Mots clés: Aberration-corrected scanning transmission electron microscopy; dead layer; EELS and EDS; oxygen vacancy; density functional theory (DFT); multislice image simulation

Domaines: Electronique; Micro et nanotechnologies/Microélectronique; Science des matériaux [cond-mat.mtrl-sci]

Piu Rajak, Daniel Knez, Sandeep Kumar Chaluvadi, Pasquale Orgiani, Giorgio Rossi, et al.. Evidence of Mn-Ion Structural Displacements Correlated to Oxygen Vacancies in La0.7Sr0.3MnO3 Interfacial Dead Layers. ACS Applied Materials & Interfaces, 2021, 13 (46), pp.55666-55675. ⟨10.1021/acsami.1c15599⟩. ⟨hal-03676023⟩