Spin transitions in La0.7 Ba0.3CoO3 thin films revealed by combining Raman spectroscopy and X-ray diffraction
Résumé
In cobaltite, the spin states transitions of Co3þ/4þ ions govern the magnetic and electronic conduction
properties. These transitions are strain-sensitive and can be varied using external parameters, including
temperature, hydrostatic pressure, or chemical stresses through ionic substitutions. In this work,
using temperature dependent Raman spectroscopy and X-ray diffraction, the epitaxial strain effects
on both structural and vibrational properties of La0.7 Ba0.3 CoO3 (LBCO) cobaltite thin films are
investigated. All Raman active phonon modes as well as the structure are found to be strongly
affected. Both Raman modes and lattice parameter evolutions show temperature changes correlated
with magnetic and electronic transitions properties. Combining Raman spectroscopy and X-ray diffraction
appears as a powerful approach to probe the spin transition in thin film cobaltite. Our results
provide insight into strong spin-charge-phonon coupling in LBCO thin film. This coupling manifests
as vibrational transition with temperature in the Raman spectra near the ferromagnetic spin ordered
transition at 220K.
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