Narcizo M. Souza-Neto

Pressure-induced electronic mixing and enhancement of ferromagnetic ordering in EuX (X=Te, Se, S, O) magnetic semiconductors.

The pressure- and anion-dependent electronic structure of EuX (X=Te, Se, S, O) monochalcogenides is probed with element- and orbital-specific x-ray absorption spectroscopy in a diamond anvil cell. An isotropic lattice contraction enhances the ferromagnetic ordering temperature by inducing mixing of Eu 4f and 5d electronic orbitals. Anion substitution (Te-->O) enhances competing exchange pathways through spin-polarized anion p states, counteracting the effect of the concomitant lattice contraction. The results have strong implications for efforts aimed at enhancing FM exchange interactions in thin films through interfacial strain or chemical substitutions.

Energy-dispersive X-ray absorption spectroscopy at LNLS: investigation on strongly correlated metal oxides

An energy-dispersive X-ray absorption spectroscopy beamline mainly dedicated to X-ray magnetic circular dichroism (XMCD) and material science under extreme conditions has been implemented in a bending-magnet port at the Brazilian Synchrotron Light Laboratory. Here the beamline technical characteristics are described, including the most important aspects of the mechanics, optical elements and detection set-up. The beamline performance is then illustrated through two case studies on strongly correlated transition metal oxides: an XMCD insight into the modifications of the magnetic properties of Cr-doped manganites and the structural deformation in nickel perovskites under high applied pressure.

Local tetragonal distortion in La0.7Sr0.3MnO3 strained thin films probed by x-ray absorption spectroscopy

We report on an angular resolved x-ray absorption spectroscopy study of

Stability of Jahn Teller distortion in LaMnO3 under pressure: An x-ray absorption study

{\mathrm{La}}_{0.7}{\mathrm{Sr}}_{0.3}{\mathrm{MnO}}_{3}

Emergence of ferromagnetism and Jahn-Teller distortion in LaMn1−xCrxO3 (x < 0.15)

thin films epitaxially grown by pulsed laser deposition on slightly mismatched substrates which induce tensile or compressive strains. XANES spectra give evidence of tetragonal distortion within the

Local atomic and electronic structure in LaMnO{sub 3} across the orbital ordering transition

{\mathrm{MnO}}_{6}

X-ray absorption spectroscopy study of FePt thin films

octahedra, with opposite directions for tensile and compressive strains. Quantitative analysis has been done and a model of tetragonal distortion reflecting the strain has been established. EXAFS data collected in plane for tensile substrate confirm the change in the

Local anisotropy in strained manganite thin films

\mathrm{Mn}\text{\ensuremath{-}}\mathrm{O}

Temperature and high-pressure dependent x-ray absorption ofSmNiO3 at the Ni K and Sm L3 edges

average bond distance and the increase of

Depth-dependent chemical and magnetic local orders in thin magnetic films

\mathrm{Mn}\text{\ensuremath{-}}\mathrm{Mn}