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Doped manganite perovskite (ultra)thin films (R1-xAxMnO3 - R = rare-earth, A = Ca, Sr, Ba and Pb) show a very rich phase diagram and are considered as model system in fundamental solid state physics [1]. Moreover ferromagnetic metallic manganites are employed as prototypical spin injectors in several systems in order to reveal insights in a variety of spin related effects [2]. The La0.7Sr0.3MnO3 (LSMO) compound has stimulated an intense study since, in bulk form, it has one of the highest ferromagnetic transition temperature TC ~ 370 K. Understanding and controlling the morpho-structural and magnetic properties of LSMO films as a function of thickness is crucial for realizing applications that commonly demand for ultrathin layers. La0.7Sr0.3MnO3 thin films, with thickness t in the 4 - 16 nm range, were deposited on (001) oriented SrTiO3 substrates by means of channel spark ablation of a stoichiometric target in oxygen atmosphere [3]. The oxygen pressure in the chamber was 3.9·10-2 mbar, the substrate temperature was around 890 °C and the deposition rate was between 0.10 and 0.15 Å per pulse for a repetition rate of 6 Hz. After the deposition the films were cooled in vacuum (5.0·10-4 mbar) down to about 400 °C, where they were in situ conditioned by an annealing before removing them from the vacuum. The film thickness was estimated by XRR measurements, which also provided information on roughness and density. Both temperature (100 K £ T £ 300 K) and angular dependence of the magnetic properties were studied by a vector Vibrating Sample Magnetometer (vVSM). Ferromagnetism is observed down to 4nm (TC ~ 250 K …
V. Dediu, L. Del Bianco
Publication date: 
1 Jan 2015

G Varvaro, P Graziosi, Lucia DEL BIANCO, AM Testa, M Calbucci, I Bergenti, F Liscio, S Milita, V Dediu

Biblio References: 
Pages: 112-112
4th Conference of the Italian Magnetism Association-Magnet 2015