3 research outputs found
Oxygen vacancies and induced changes in the electronic and magnetic structures of La0.66Sr0.33MnO3: A combined ab initio and photoemission study
The effect of oxygen vacancies on the electronic and magnetic properties of La0.66Sr0.33MnO3 LSMO has
been investigated by means of ab initio calculations within the density-functional formalism combined with
photoemission. The simulations show that the introduction of oxygen vacancies causes a shift of the valenceband
features toward higher binding energies and an increase of the degree of covalency of Mn bondings. The
Mn magnetic moments undergo some changes, keeping, however, the situation relatively close to the ideal
nondefective system: in none of the different vacancy configurations, a drastic charge or spin rearrangement
occurs. There is, though, an important vacancy-induced drawback: half-metallicity, typical of the perfectly
stoichiometric system, is generally lost due to defective bands that cross the Fermi level. Photoemission
experiments performed on epitaxial thin films of LSMO with different contents of oxygen vacancies grown by
pulsed laser deposition essentially confirm theoretical predictions. Our findings clearly indicate that the control
over oxygen deficiency should therefore be experimentally achieved to avoid unwanted consequences in terms
of spin-injection efficiency
Proximity effects induced by a gold layer on La0.67Sr0.33MnO3 thin films
We report about La0.67Sr0.33MnO3 single crystal manganite thin films in
interaction with a gold capping layer. With respect to uncoated manganite
layers of the same thickness, Au-capped 4 nm-thick manganite films reveal a
dramatic reduction (about 185 K) of the Curie temperature TC and a lower
saturation low-temperature magnetization M0. A sizeable TC reduction (about 60
K) is observed even when an inert SrTiO3 layer is inserted between the gold
film and the 4 nm-thick manganite layer, suggesting that this effect might have
an electrostatic origin