Origin of itinerant carriers in antiferromagnetic LaF e 1 − x M o x O 3 studied by x-ray spectroscopies

DOI: 10.1103/PhysRevMaterials.4.034405

Authors: Dibya Phuyal (Uppsala University) , Soham Mukherjee (Uppsala University) , S. K. Panda (Bennet University) , Somnath Jana (Uppsala Univesity) , Carlo U. Segre (Illinois Institute of Technology) , Laura Simonelli (CELLS-ALBA Synchrotron) , Sergei M. Butorin (Uppsala University) , Hakan Rensmo (Uppsala University) , Olof Karis (Uppsala University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review Materials , VOL 4 , PAGES 034405

State: Published (Approved)
Published: March 2020
Diamond Proposal Number(s): 22648

Abstract: 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.

Journal Keywords: antiferromagnetism; electronic structure; strongly correlated systems; hard x-ray photoemission spectroscopy

Subject Areas: Physics, Materials, Information and Communication Technology


Instruments: I09-Surface and Interface Structural Analysis

Other Facilities: BL8 at ALS (USA); Sector 10 at APS (USA)

Documents:
PhysRevMaterials.4.034405.pdf

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