Impurities in multiband superconductors
a L.V. Kirenskii Institute of Physics, Siberian Branch of the Russian Academy of Sciences, Academgorodok 50, stroenie 38, Krasnoyarsk, 660036, Russian Federation
b Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Straße 38, Dresden, D-01187, Germany
c Siberian Federal University, pr. Svobodnyi 79, Krasnoyarsk, 660041, Russian Federation
d Lebedev Physical Institute, Russian Academy of Sciences, Leninsky prosp. 53, Moscow, 119991, Russian Federation
e Max-Planck Institut für Festkörperforschung, Stuttgart, Germany
Disorder — impurities and defects violating the ideal order — is always present in solids. It can result in interesting and sometimes unexpected effects in multiband superconductors. Especially if the superconductivity is unconventional thus having other than usual s-wave symmetry. This paper uses the examples of iron-based pnictides and chalcogenides to examine how both nonmagnetic and magnetic impurities affect superconducting states with s± and s++ order parameters. We show that disorder causes the transition between s± and s++ states and examine what observable effects this transition can produce.