Origin of itinerant carriers in antiferromagnetic LaFe1-xMoxO3 studied by x-ray spectroscopies

• We report on the electronic structure of doped LaFeO3 at the crossover from an insulating-to-metallic phase transition. Comprehensive x-ray spectroscopic methodologies are used to understand core and valence electronic structure as well as crystal structure distortions associated with the electronic transition. Despite the antiferromagnetic (AFM) ordering at room temperature, we show direct evidence of itinerant carriers at the Fermi level revealed by resonant photoemission spectroscopy (RPES) at the Mo L3 edge. RPES data taken at the Fe L3 edge show spectral weight near the valence band edge and significant hybridization with O 2p states required for AFM ordering. Resonant inelastic x-ray scattering spectra taken across Fe L2,3 edges show electron correlation effects (U) driven by Coulomb interactions of d electrons as well as broad charge-transfer excitations for x≥0.2 where the compound crosses over to a metallic state. Site substitution of Fe by Mo ions in the Fe-O6 octahedra enhances the separation of the two Fe-O bonds and Fe-O-Fe bonding angles relative to the orthorhombic LaFeO3, but no considerable distortions are present to the overall structure. Mo ions appear to be homogeneously doped, with average valency of both metal sites monotonically decreasing with increasing Mo concentration. This insulator-to-metal phase transition with AFM stability is primarily understood through intermediate interaction strengths between correlation (U) and bandwidth (W) at the Fe site, where an estimation of this ratio is given. These results highlight the important role of extrinsic carriers in stabilizing a unique phase transition that can guide future efforts in antiferromagnetic-metal spintronics.

Ämnesord

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

Nyckelord

antiferromagnetism

electronic structure

magnetism

x-ray spectroscopy

Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik

Physics with spec. in Atomic, Molecular and Condensed Matter Physics

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