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TT: Fachverband Tiefe Temperaturen

TT 53: Poster Session: Superconductivity 1

TT 53.16: Poster

Mittwoch, 22. März 2017, 15:00–19:00, P2-OG2

Doping effect of Mn impurities on the physical properties of optimally electron doped Sr(Fe_0.86Co_0.14)₂As₂ — •Luminita Harnagea, Giri Mani, and Surjeet Singh — Indian Institute of Science Education and Research, Pune - 411008, India.

Using transport and magnetization measurements we studied the effect of Mn doping in optimally electron doped Sr(Fe_0.86Co_0.14)₂As₂ single crystal. The as - grown Sr(Fe_0.86Co_0.14)₂As₂ single crystal exhibits a superconducting transition temperature (T_c) of around 15 K. Doping with Mn at the Fe site in Sr(Fe_0.86Co_0.14)₂As₂ leads to a gradual suppression of the transition temperature with an initial rate of about ΔT_c   5 K per Mn percentage. The residual resistivity of the doped samples increases with increasing Mn concentration. The low-temperature magnetic susceptibility of the Mn-doped samples exhibits a Curie tail, which gets progressively enhanced with increasing Mn - concentration, suggesting that the Mn - ions carry a localized magnetic moment consistent with S = 1/2 local moment. The paramagnetic Mn moments act as Cooper pair-breakers resulting in a gradual suppression of T_c, analogous to Ba(Fe_1−x−yCo_xMn_y)₂As₂ series of compounds [1]. These results are, however, in stark contrast with the case of Mn doped LaFeAsO_0.89F_0.11, where a Mn concentration as small as 0.2 %, suppresses the superconductivity completely [2]. These differences are rather surprising and their more detailed understanding might throw light on the nature of superconducting state in iron pnictides.

[1] D. LeBoeuf et al., Phys. Rev. B 89, 035114 (2014)

[2] F. Hammerath et al., Phys. Rev. B 89, 134503 (2014)