Orbital characters determined from Fermi surface intensity patterns using angle-resolved photoemission spectroscopy

Abstract

In order to determine the orbital characters on the various Fermi surface pockets of the Fe-based superconductors Ba0.6K0.4Fe2As2 and FeSe0.45Te0.55, we introduce a method to calculate photoemission matrix elements. We compare our simulations to experimental data obtained with various experimental configurations of beam orientation and light polarization. We show that the photoemission intensity patterns revealed from angle-resolved photoemission spectroscopy measurements of Fermi surface mappings and energy-momentum plots along high-symmetry lines exhibit asymmetries carrying precious information on the nature of the states probed, information that is destroyed after the data symmetrization process often performed in the analysis of angle-resolved photoemission spectroscopy data. Our simulations are consistent with Fermi surfaces originating mainly from the dxy, dxz and dyz orbitals in these materials.

Functional renormalization group for multi-orbital Fermi surface instabilities

“…Taken together, the relevant electrons in the FeSCs are more delocalized than in the cuprates and effectively give rise to smaller electronic correlation effects. In this context, it is also interesting to note that the calculated band structure [69][70][71][72] agrees well (not in all, but in many cases) with the one determined by ARPES [73][74][75] and quantum oscillation measurements [76,77], which can be interpreted as another evidence for weaker correlation effects in FeSCs.…”

“…Here,Ô ch k denotes the respective bosonic operators defined in (75), and the corresponding eigenmode f ch i (k) gives detailed information on the real-space ordering pattern (see Appendix 6.4) as well as on the one-particle spectrum within the symmetry broken phase. At sufficiently low energy scales of the flow, the four-point function γ (4) or, respectively, the coupling function V Λ starts to diverge and thus signals the possible onset of spontaneous symmetry breaking.…”

The orbital characters of low-energy electronic structure in iron-chalcogenide superconductor K x Fe2−y Se2

“…The α, β, γ, δ, and δ bands are dominated by similar orbitals in K x Fe 2−y Se 2 and other iron-based superconductors [27,28]. However, the δ and δ bands are weakly hybridized in K x Fe 2−y Se 2 , instead of being strongly hybridized in the other iron-based superconductors.…”

“…Polarization-dependent ARPES experiments have been conducted extensively on the iron-based superconductors, including LaOFeAs [13], BaFe 2 As 2 [23][24][25][26][27], NaFeAs [28,29], and FeTe [17,27]. Here we report the polarization-dependent ARPES study on the orbital characters of K x Fe 2−y Se 2 superconductor.…”

Observation of strong electron pairing on bands without Fermi surfaces in LiFe1−xCoxAs

“…To quantify the k z effect of the a band and confirm that it does not cross E F along k z , we extract the NS dispersion of the a band at k z ¼ 0 and p. Figure 3a,c shows the ARPES intensity plots of 3% Co at 51 eV (k z ¼ 0) and 35 eV (k z ¼ p), respectively. The data are recorded at 20 K with linearly polarized light to enhance the intensity of the a band 11,17 . The intensity plots and EDCs show that the band top of the a band has tiny dispersion along k z and prove that at least for 3% Co, the a band is completely sinking below E F all over the momentum space.…”