Electronic structure ofLaO1−xFxBiSe2(x=

Abstract

We report an electronic structure study on LaO1-xFxBiSe2 (x = 0.18) by means of photoelectron spectromicroscopy. The Fermi surfaces and band dispersions are basically consistent with the band-structure calculations on BiS2-based materials, indicating that the electron correlation effects may be irrelevant to describe physics of the new BiSe2 system. In LaO1-xFxBiSe2 (x = 0.18), the area of the Fermi pockets is estimated to be 0.16 +/- 0.02 per Bi, consistent with the amount of F substitution. Although the spectromicroscopy technique avoids the effect of microscale inhomogeneity for angle-resolved photoemission spectroscopy (ARPES), the ARPES spectral features are rather broad in the momentum space, indicating the likely effect of local disorder in the BiSe2 layer

Metallic phase in stoichiometric CeOBiS2 revealed by space-resolved ARPES

“…Incidentally, we have found metallic phase embedded in the morphological defects and at the sample edges. This metallic phase is characterized by the usual electron Fermi surface pocket at X point, similar to the doped BiS 2 -based superconductors 22–25 . This unexpected result may provide a possible way to understand the observed superconductivity in undoped CeOBiS 2 .…”

“…The Fermi surface maps clearly show that the majority phase (region B) is non-metallic while the minority phase (region A) is metallic. Indeed, the typical Fermi surfaces of the doped BiS 2 -based systems 11,24,25 , characterized by the electron pockets around X point, can be clearly seen in Fig. 3(a) whereas it is absent in Fig.…”

“…The space-resolved ARPES results have clearly shown that metallic phase appears embedded in the majority texture of semiconducting phase in CeOBiS 2 . The electronic structure of the metallic phase is characterized by dispersing band structure and Fermi surface pocket around the X point of Bi 6 p x,y nature, typical of doped BiS 2 -based superconducting materials 11,24,25 . Incidentally, the metallic phase is found only around the morphological defects in the crystal while the majority of the sample is highly homogeneous and reveals usual semiconducting characteristics of BiS 2 -based systems without doping or self-doping 10 .…”

RVB states in doped band insulators from Coulomb forces: theory and a case study of superconductivity in BiS2layers

“…This is likely to be a gapful d xy state as fermi surfaces are fragmented. as seen in ARPES experiments [42][43][44][45][46]. That is, nodal lines pass between fermi surfaces.…”

Electronic structure of self-doped layeredEu3F4Bi2S4material revealed by x-ray absorption spectroscopy and photoelectron spectromicroscopy

“…Both maps were integrated within ±80 meV. The topology of the Fermi surfaces is the same as the RE(O,F)BiS 2 and RE(O,F)BiSe 2 systems [6,18,19], indicating that the part of electrons in Eu was introduced to the Bi 6p x /6p y orbitals. The weak intensity around −0.17 < E < 0 eV (=E F ) may be related to the existence of structural instability in a tetragonal BiS 2 layer [10,11,20,21].…”