Electronic structure studies ofBaFe2As2by angle-resolved photoemission spectroscopy

Abstract

We report high resolution angle-resolved photoemission spectroscopy ͑ARPES͒ studies of the electronic structure of BaFe 2 As 2 , which is one of the parent compounds of the Fe-pnictide superconductors. ARPES measurements have been performed at 20 and 300 K, corresponding to the orthorhombic antiferromagnetic phase and the tetragonal paramagnetic phase, respectively. Photon energies between 30 and 175 eV and polarizations parallel and perpendicular to the scattering plane have been used. Measurements of the Fermi surface yield two hole pockets at the ⌫ point and an electron pocket at each of the X points. The topology of the pockets has been concluded from the dispersion of the spectral weight as a function of binding energy. Changes in the spectral weight at the Fermi level upon variation in the polarization of the incident photons yield important information on the orbital character of the states near the Fermi level. No differences in the electronic structure between 20 and 300 K could be resolved. The results are compared with density functional theory band structure calculations for the tetragonal paramagnetic phase.

Analysis of spin-density wave conductivity spectra of iron pnictides in the framework of density functional theory

“…As for the nature of the AF state, the iron pnictides show signatures of both electron itinerancy and local magnetism. Some experimental [5][6][7][8][9][10][11] and theoretical works based on density functional theory (DFT) [12][13][14][15][16][17][18] and dynamical mean-field theory (DMFT) 19 as well as a combination of these two methods 20,21 favor an itinerant scenario with rather moderate correlation strength, as reflected by the metallic nature of the compounds. On the other hand, other authors point out the effects of strong correlations, [22][23][24][25][26][27] like the renormalization of the kinetic energy of the electrons.…”

Fermi surfaces of iron pnictide high-Tcsuperconductors from the limit of local magnetic moments

“…The charge carriers in these systems have predominantly iron 3d-orbital character [3][4] [5], and they exist at twodimensional (2D) hole-type and electron-type Fermi surface pockets centered, respectively, at zero 2D momentum and at the 2D cSDW momenta (h/2a)x(ŷ) [6][7] [8]. Here, a is the iron 2D lattice constant.…”

Dynamical Correlations and Screened Exchange on the Experimental Bench: Spectral Properties of the Cobalt PnictideBaCo2As2

“…The discovery of unconventional superconductivity in iron pnictides and chalcogenides in 2008 has aroused strong interest into the Fermi surfaces and low-energy excitations of transition metal pnictides and related compounds. Angle-resolved photoemission spectroscopy (ARPES) has been used to systematically map out quasiparticle dispersions, and to identify electron and hole pockets potentially relevant for low-energy instabilities [1][2][3][4][5][6][7]. Density functional theory (DFT) calculations have complemented the picture, yielding information about orbital characters [8], or the dependence of the topology of the Fermi surface on structural parameters or element substitution [9,10].…”