Direct observation of strong correlations near the band insulator regime of Bi misfit cobaltates

Abstract

We present the first angle-resolved photoemission (ARPES) measurement of Fermi Surface in the "misfit" cobaltate [Bi2Ba2O4].[CoO2]~2. This compound contains the same triangular Co planes as Na cobaltates, but in a different 3D environment. Our data establish the similarity of their electronic structure. We propose that the peculiar lineshape of all cobaltates is of the "peak-dip-hump" type, due to strong many-body effects. We detect a progressive transfer of spectral weight from the quasiparticle feature near Ef to a broad hump in misfit phases where Ba is replaced by Sr or Ca. This indicates stronger many-body interactions in proximity of the band insulator regime, which we attribute to the presence of unusual magnetic excitations.

4 pages, 4 figures

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• Fermi surface evolution and Luttinger theorem in Na${}_x$CoO${}_2$: a systematic photoemission study
• Anomalous high energy dispersion in photoemission spectra from insulating cuprates
• Low-lying quasiparticle states and hidden collective charge instabilities in parent cobaltate superconductors (NaxCoO2)
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• Normal state electronic structure in the heavily overdoped regime of Bi1.74Pb0.38Sr1.88CuO6+delta single-layer cuprate superconductors

Cited by in corpus (5)

• Interplay between magnetic properties and thermoelectricity in misfit and Na cobaltates
• The origin of strong correlations and superconductivity in Na${}_x$CoO${}_2$
• Spin polaron theory for the photoemission spectra of layered cobaltates
• Novel electronic structure induced by a highly strained oxide interface with incommensurate crystal fields
• Metal-nonmetal transition in LixCoO2 thin film and thermopower enhancement at high Li concentration