Probing the pairing symmetry of the iron pnictides with electronic Raman scattering

Abstract

An important issue in the study of the iron-arsenic based superconductors is the symmetry of the superconducting gap, a problem complicated by multiple gaps on different Fermi surface sheets. Electronic Raman scattering is a flexible bulk probe which allows one in principle to determine gap magnitudes and test for gap nodes in different regions of the Brillouin zone by employing different photon polarization states. Here we calculate the clean Raman intensity for A1g, B1g and B2g polarizations, and discuss the peak structures and low-energy power laws which might be expected for several popular models of the superconducting gap in these systems.

Impact of the spin-density-wave order on the superconducting gap ofBa(Fe1−xCox)Chauviere1, Gallais2, Cazayous3 et al. 2010Phys. Rev. B3615500View full textAdd to dashboardCite

“…The theoretical fit in blue was obtained using an anisotropic gap (see text), a broadening γ = 0.1∆max and a constant B2g Raman vertex around the electron pocket [14]. The theoretical fit in black was obtained using two isotropic gaps 2∆1, 2∆2(dashed lines), a broadening γ = 0.3∆2.…”

Robust accidental nodes and zeros and critical quasiparticle scaling in iron-based multiband superconductors

“…As stressed above, both nodal and nodeless states belong to the native A 1g representation of the lattice rotation group and the appearance of nodes is a direct consequence of the orbital anisotropy of the effective interactions. This model emulates the physics of iron-pnictides and its different versions have been used in that context [23][24][25][26] . A summary of our results is as follows: i) The gap structure obtained at T = T c is fairly robust as a function of T and, in particular, if nodes exist near T c they can survive as T → 0; ii) at the zero-points ∆ ′ = ∆ 0 , there are gapless quasiparticle excitations with unusual anisotropic dispersion.…”

Raman resonance in iron-based superconductors: The magnetic scenario

“…[1][2][3][4][5][6][7][8]). The subject of this paper is the theoretical analysis of the features in Raman scattering revealed by polarization-sensitive Raman spectroscopy in the normal and the superconducting states of Fe-based materials NaFe 1−x Co x As [9], AFe 2 As 2 , A =Eu,Sr [10 and 11], and Ba(Fe 1−x Co x ) 2 As 2 [12 and 13].…”

“…The subject of this paper is the theoretical analysis of the features in Raman scattering revealed by polarization-sensitive Raman spectroscopy in the normal and the superconducting states of Fe-based materials NaFe 1−x Co x As [9], AFe 2 As 2 , A =Eu,Sr [10 and 11], and Ba(Fe 1−x Co x ) 2 As 2 [12 and 13]. Polarized light was used to probe the Raman response in different symmetry channels, classified by the irreducible representations of the D 4h crystallographic point group [1]. In the normal state the real part of the (almost) static and uniform Raman susceptibility in the B 1g channel in one-iron unit cell notation (same as the B 2g channel in two-iron notation used in Refs.…”