Eur. Phys. J. Special Topics 228, 719–723 (2019)
https://doi.org/10.1140/epjst/e2019-800144-1

Regular Article

Electrodynamic response of Ba(Fe_1−xRh_x)₂As₂ across the s_± to s₊₊ order parameter transition

¹ Politecnico di Torino, Department of Applied Science and Technology, Torino 10129, Italy
² Istituto Nazionale di Fisica Nucleare, Sezione di Torino, Torino 10125, Italy
³ Ames Laboratory, US Department of Energy, Ames, IA 50011, USA
⁴ Department of Physics & Astronomy, Iowa State University, Ames, IA 50011, USA

^a e-mail: daniele.torsello@polito.it

Received: 11 September 2018
Received in final form: 30 November 2018
Published online: 3 July 2019

Abstract

Most iron-based superconductors are characterized by the s_± symmetry of their order parameter, and are expected to go through a transition to the s₊₊ state if enough disorder is introduced. We previously reported the observation of this transition in Ba(Fe_1−xRh_x)₂As₂ through a study of the disorder dependence of the critical temperature and low-temperature London penetration depth. In this paper we report on the analysis of the electrodynamic response of the same sample across the transition and we identify peculiarities in the behaviour of the surface resistance and normal conductivity, that can be considered as traces of the transition itself.