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Influence of film thickness and strain on magnetic properties of epitaxial La 0.7 A 0.3 CoO 3 (A = Ca, Sr, Ba) thin films
Author(s) -
Morán O.,
Fuchs D.,
Adelmann P.,
Schneider R.
Publication year - 2004
Publication title -
annalen der physik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.009
H-Index - 68
eISSN - 1521-3889
pISSN - 0003-3804
DOI - 10.1002/andp.200310053
Subject(s) - condensed matter physics , hall effect , curie temperature , materials science , ferromagnetism , hydrostatic pressure , electrical resistivity and conductivity , thin film , epitaxy , magnetization , magnetic field , physics , composite material , thermodynamics , nanotechnology , quantum mechanics , layer (electronics)
We prepared La 0.7 A 0.3 CoO 3 (A=Ca, Sr, Ba) films with a thickness ranging from 50 up to 1000 monolayers (∼ 20–400 nm) by pulsed laser deposition (PLD) on (001)‐oriented single crystal substrates of SrTiO 3 , (LaAlO 3 ) 0.3 (Sr 2 AlTaO 6 ) 0.7 and LaAlO 3 and studied the in‐plane and out‐of‐plane magnetization as function of thickness and of the strain provided by the substrate‐film lattice mismatch. The Curie temperature T C decreases slightly with thickness according to the finite size scaling 1 – T C / T ∞ = ( N 0 / N ) λ , where T ∞ is the bulk Curie temperature and N is the number of monolayers. We obtain a critical exponent λ = 0.9 ± 0.2, consistent with the theoretical mean field value, and a spin‐spin coupling range N 0 = 2–3.