Impurity-induced smearing of the spin resonance peak in Fe-based superconductors

The spin resonance peak in the iron-based superconductors is observed in inelastic neutron scattering experiments and agrees well with predicted results for the extended s-wave ($s_\pm$) gap symmetry. On the basis of four-band and three-orbital tight binding models we study the effect of nonmagnetic disorder on the resonance peak. Spin susceptibility is calculated in the random phase approximation with the renormalization of the quasiparticle self-energy due to the impurity scattering in the static Born approximation. We find that the spin resonance becomes broader with the increase of disorder and its energy shifts to higher frequencies. For the same amount of disorder the spin response in the $s_\pm$ state is still distinct from that of the $s_{++}$ state.Comment: 4 pages, 2 figure

Spin resonance peak in Fe-based superconductors with unequal gaps

We study the spin resonance in the superconducting state of iron-based materials within multiband models with two unequal gaps, ΔL and ΔS, on different Fermi-surface pockets. We show that, due to the indirect nature of the gap entering the spin susceptibility at the nesting wave vector Q, the total gap Δ˜ in the bare susceptibility is determined by the sum of gaps on two different Fermi-surface sheets connected by Q. For the Fermi-surface geometry characteristic of most iron pnictides and chalcogenides, the indirect gap is either Δ˜=ΔL+ΔS or Δ˜=2ΔL. In the s++ state, spin excitations below Δ˜ are absent unless additional scattering mechanisms are assumed. The spin resonance appears in the s± superconducting state at frequency ωR≤Δ˜. Comparison with available inelastic neutron-scattering data confirms that what is seen is the true spin resonance and not a peak inherent to the s++ state

Impurity-Induced Smearing of the Spin Resonance Peak in Fe-Based Superconductors

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.The spin resonance peak in the iron-based superconductors is observed in inelastic neutron scattering experiments and agrees well with predicted results for the extended s-wave (s±) gap symmetry. On the basis of four-band and three-orbital tight-binding models we study the effect of nonmagnetic disorder on the resonance peak. Spin susceptibility is calculated in the random-phase approximation with the renormalization of the quasiparticle self-energy due to the impurity scattering in the static Born approximation. We find that the spin resonance becomes broader with the increase of disorder and its energy shifts to higher frequencies. For the same amount of disorder the spin response in the s± state is still distinct from that of the s++ state

Uniform Impurity Scattering in Two-Band s± and s++ Superconductors

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.The s± and s++ models for the superconducting state are subject of intense studies regarding Fe-based superconductors. Depending on the parameters, disorder may leave intact or suppress T c in these models. Here, we study the special case of disorder with equal values of intra- and interband impurity potentials in the two-band s± and s++ models. We show that this case can be considered as an isolated point and Tc there has maximal damping for a wide range of parameters

Spin resonance peak in Fe-based superconductors with unequal gaps

We study the spin resonance in the superconducting state of iron-based materials within multiband models with two unequal gaps, ΔL and ΔS, on different Fermi-surface pockets. We show that, due to the indirect nature of the gap entering the spin susceptibility at the nesting wave vector Q, the total gap Δ˜ in the bare susceptibility is determined by the sum of gaps on two different Fermi-surface sheets connected by Q. For the Fermi-surface geometry characteristic of most iron pnictides and chalcogenides, the indirect gap is either Δ˜=ΔL+ΔS or Δ˜=2ΔL. In the s++ state, spin excitations below Δ˜ are absent unless additional scattering mechanisms are assumed. The spin resonance appears in the s± superconducting state at frequency ωR≤Δ˜. Comparison with available inelastic neutron-scattering data confirms that what is seen is the true spin resonance and not a peak inherent to the s++ state

Uniform Impurity Scattering in Two-Band s± and s++ Superconductors

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.The s± and s++ models for the superconducting state are subject of intense studies regarding Fe-based superconductors. Depending on the parameters, disorder may leave intact or suppress T c in these models. Here, we study the special case of disorder with equal values of intra- and interband impurity potentials in the two-band s± and s++ models. We show that this case can be considered as an isolated point and Tc there has maximal damping for a wide range of parameters