abstract
Epitaxial La0.7Sr0.3MnO3 (LSMO) thin films, with different thicknesses ranging from 20 to 330 nm, were deposited on (1 0 0)-oriented strontium titanate (STO) substrates by pulsed laser deposition, with their structure and morphology characterized at room temperature. The magnetic and electric transport properties of the as-processed thin films reveal an abnormal behaviour in the temperature dependent magnetization M(T) below the antiferrodistortive STO phase transition (T-STO), and also an anomaly in the magnetoresistance and electrical resistivity close to the same temperature. Films with thickness <= 100 nm show an in-excess magnetization and pronounced changes in the coercivity due to the interface-mediated magnetoelastic coupling with antiferrodistortive domain wall movement occurring below T-STO. However, in thicker LSMO thin films, an in-defect magnetization is observed. This reversed behaviour can be understood with the emergence in the upper layer of the film, of a columnar structure needed to relax the elastic energy stored in the film, which leads to randomly oriented magnetic domain reconstructions. For enough high-applied magnetic fields, as thermodynamic equilibrium is reached, a full suppression of the anomalous magnetization occurs, wherein the temperature dependence of the magnetization starts to follow the expected Brillouin behaviour.
keywords
LATTICE-DISTORTIONS; DIFFRACTION; MANGANITES; EPITAXY
subject category
Physics
authors
Mota, DA; Barcelay, YR; Senos, AMR; Fernandes, CM; Tavares, PB; Gomes, IT; Sa, P; Fernandes, L; Almeida, BG; Figueiras, F; Vaghefi, PM; Amaral, VS; Almeida, A; de la Cruz, JP; Moreira, JA
our authors
Groups
G2 - Photonic, Electronic and Magnetic Materials
G3 - Electrochemical Materials, Interfaces and Coatings
Projects
Multiferroics and magnetoelectrics for spintronics: barriers and interfaces (PTDC/CTM/099415/2008)
acknowledgements
This work was supported by the Fundacao para a Ciencia e Tecnologia and COMPETE/QREN/EU, through the project PTDC/CTM/099415/2008. The authors are very grateful to Maria Joao Pereira and Maria Rosario Soares from CICECO, University of Aveiro, for the HR-XRD measurements and discussion of the results. F Figueiras acknowledges FCT grant SFRH/BPD/80663/2011. The authors also acknowledge Projeto Norte-070124-FEDER-000070 and Professor J Fontcuberta for their fruitful discussions.