Regensburg 2016 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

TT: Fachverband Tiefe Temperaturen

TT 79: Superconductivity: Fe-based Superconductors - 122

TT 79.4: Vortrag

Donnerstag, 10. März 2016, 16:15–16:30, H21

Coexistence of superconductivity and magnetism in Ca_1−xNa_xFe₂As₂: Universal suppression of the magnetic order parameter in 122 iron pnictides — •Philipp Materne¹, Sirko Kamusella¹, Rajib Sarkar¹, Luminita Harnagea², Sabine Wurmehl^1,2, Bernd Büchner^1,2, Hubertus Luetkens³, Carsten Timm⁴, and Hans-Henning Klauss¹ — ¹IFP, TU Dresden, 01062 Dresden, Germany — ²IFW Dresden, Postfach 270016, 01171 Dresden, Germany — ³PSI, 5232 Villigen, Switzerland — ⁴ITP, TU Dresden, 01062 Dresden, Germany

We examined Ca_1−xNa_xFe₂As₂ single crystals with x = 0.00, 0.35, 0.50, and 0.67 by means of muon spin relaxation and Mössbauer spectroscopy to investigate the electronic and structural properties of these compounds. CaFe₂As₂ is a semimetal, which shows spin density wave order below 167 K. By hole doping via Ca→Na substitution, the magnetic order is suppressed and superconductivity emerges with T_c ≈ 34 K at optimal doping including a substitution level region where both phases coexist. We have studied the interplay of order parameters in this coexistence region and found nanoscopic coexistence of both order parameters. This is proven by a reduction of the magnetic order parameter by 7 % below the superconducting transition temperature. We present a systematic correlation between the reduction of the magnetic order parameter and the ratio of the transition temperatures, T_c/T_N, for the 122 family of the iron-based superconductors [1].