Saurabh Maiti

Evolution of the superconducting state of Fe-based compounds with doping.

We introduce an effective low-energy pairing model for Fe-based superconductors with s- and d-wave interaction components and a small number of input parameters and use it to study the doping evolution of the symmetry and the structure of the superconducting gap. We argue that the model describes the entire variety of pairing states found so far in the Fe-based superconductors and allows one to understand the mechanism of the attraction in s(±) and d(x(2)-y(2)) channels, the competition between s- and d-wave solutions, and the origin of superconductivity in heavily doped systems, when only electron or only hole pockets are present.

Effect of fermi surface nesting on resonant spin excitations in Ba 1-xKxFe2As2

We report inelastic neutron scattering measurements of the resonant spin excitations in Ba(1-x)K(x)Fe(2)As(2) over a broad range of electron band filling. The fall in the superconducting transition temperature with hole doping coincides with the magnetic excitations splitting into two incommensurate peaks because of the growing mismatch in the hole and electron Fermi surface volumes, as confirmed by a tight-binding model with s(±)-symmetry pairing. The reduction in Fermi surface nesting is accompanied by a collapse of the resonance binding energy and its spectral weight, caused by the weakening of electron-electron correlations.

Evolution of symmetry and structure of the gap in iron-based superconductors with doping and interactions

We present a detailed study of the symmetry and structure of the pairing gap in Fe-based superconductors (FeSCs). We treat FeSCs as quasi-2D, decompose the pairing interaction in the

Renormalization group flow, competing phases, and the structure of superconducting gap in multiband models of iron-based superconductors

XY

Gap nodes induced by coexistence with antiferromagnetism in iron-based superconductors

plane in

Gap symmetry in KFe 2 As 2 and the cos 4 θ gap component in LiFeAs

s

How many quantum phase transitions exist inside the superconducting dome of the iron pnictides

-wave and

Spontaneous currents in a superconductor with s+is symmetry

d

Collective modes in two- and three-dimensional electron systems with Rashba spin-orbit coupling

-wave channels into contributions from scattering between different Fermi surfaces, and analyze how each scattering evolves with doping and input parameters. We verify that each interaction is well approximated by the lowest angular harmonics. We use this simplification to analyze the interplay between the interaction with and without spin-fluctuation components, the origin of the attraction in the

Superconductivity from repulsive interaction

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