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arXiv · 0706.3849

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

V. Brouet·A. Nicolaou·M. Zacchigna·A. Tejeda·L. Patthey·S. Hebert·W. Kobayashi·H. Muguerra·D. Grebille
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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.

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V. Brouet, A. Nicolaou, M. Zacchigna, A. Tejeda, L. Patthey, S. Hebert, W. Kobayashi, H. Muguerra, D. Grebille. 2007-06-26. Direct observation of strong correlations near the band insulator regime of Bi misfit cobaltates. https://doi.org/10.1103/physrevb.76.100403

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