Theory of Andreev reflection in a two-orbital model of iron-pnictide superconductors
نویسندگان
چکیده
A recently developed theory for the problem of Andreev reflection between a normal metal (N) and a multiband superconductor (MBS) assumes that the incident wave from the normal metal is coherently transmitted through several bands inside the superconductor. Such splitting of the probability amplitude into several channels is the analogue of a quantum waveguide. Thus, the appropriate matching conditions for the wave function at the N/MBS interface are derived from an extension of quantum waveguide theory. Interference effects between the transmitted waves inside the superconductor manifest themselves in the conductance. We provide results for a FeAs superconductor, in the framework of a recently proposed effective two-band model and two recently proposed gap symmetries: in the signreversed s-wave (∆cos(kx) cos(ky)) scenario resonant transmission through surface Andreev bound states (ABS) at nonzero energy is found as well as destructive interference effects that produce zeros in the conductance; in the extended s-wave (∆ [cos(kx) + cos(ky)]) scenario no ABS at finite energy are found.
منابع مشابه
Point-contact spectroscopic studies on normal and superconducting AFe2As2-type iron pnictide single crystals
Point-contact Andreev reflection spectroscopy is applied to investigate the gap structure in iron pnictide single-crystal superconductors of the AFe2As2 (A = Ba, Sr) family (‘Fe-122’). The observed point-contact junction conductance curves, G(V ), can be divided into two categories: one where Andreev reflection is present for both (Ba0.6K0.4)Fe2As2 and Ba(Fe0.9Co0.1)2As2, and the other with a V...
متن کاملModel for the magnetic order and pairing channels in Fe pnictide superconductors.
A two-orbital model for Fe-pnictide superconductors is investigated using computational techniques on two-dimensional square clusters. The hopping amplitudes are derived from orbital overlap integrals, or by band structure fits, and the spin frustrating effect of the plaquette-diagonal Fe-Fe hopping is remarked. A spin striped state is stable in a broad range of couplings in the undoped regime,...
متن کاملAnisotropy of electrical transport in pnictide superconductors studied using Monte Carlo simulations of the spin-fermion model.
An undoped three-orbital spin-fermion model for the Fe-based superconductors is studied via Monte Carlo techniques in two-dimensional clusters. At low temperatures, the magnetic and one-particle spectral properties are in agreement with neutron and photoemission experiments. Our main results are the resistance versus temperature curves that display the same features observed in BaFe(2)As(2) det...
متن کامل