Spin resonance peak in Fe-based superconductors with unequal gaps
URI (for links/citations):http://elib.sfu-kras.ru/handle/2311/27948
Korshunov, M. M.
Shestakov, V. A.
Togushova, Yu. N.
Институт инженерной физики и радиоэлектроники
Кафедра теоретической физики и волновых явлений
Journal Name:Physical Review B - Condensed Matter and Materials Physics
Journal Quartile in Scopus:Q1
Bibliographic Citation:Korshunov, M. M. Spin resonance peak in Fe-based superconductors with unequal gaps [Текст] / M. M. Korshunov, V. A. Shestakov, Yu. N. Togushova // Physical Review B - Condensed Matter and Materials Physics. — 2016. — Т. 94. — С. 094517-1--5
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.