Berlin 2018 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 35: Superconductivity: Fe-based Superconductors - 122 and Theory

TT 35.7: Talk

Tuesday, March 13, 2018, 11:00–11:15, A 053

Interplay of magnetism and superconductivity in the triclinic Ca₁₀Pt₃As₈(Fe_1−xPt_xAs)₁₀ system — •Felix Brückner¹, Vadim Grinenko¹, Rajib Sarkar¹, Maksym Surmach¹, Hubertus Luetkens², Dmytro Inosov¹, and Hans-Henning Klauss¹ — ¹Institut für Festkörper- und Materialphysik, Technische Universität Dresden, Germany — ²Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, Villigen, Switzerland

Among iron-based superconductors, Ca₁₀Pt₃As₈(Fe_1−xPt_xAs)₁₀ is the first system with a triclinic crystal structure. The usually tetragonal symmetry of the characteristic FeAs layers is slightly distorted by insertion of a skutterudite-like interlayer.

We report comprehensive studies of magnetic probe experiments including ⁷⁵As and ¹⁹⁵Pt nuclear magnetic resonance (NMR), muon spin rotation and inelastic neutron scattering (INS). Broadening of NMR spectra below T^∗ ∼ 45 K provides evidence for static magnetic correlations far above the superconducting T_c = 13 K. At T^∗, a sudden drop of the spin-lattice relaxation rate, that is insensitive to external magnetic field up to 30 T, is observed. INS spectra exhibit a resonant mode at higher energies just below T^∗. This was previously interpreted as a manifestation of preformed cooper pairs, which can be ruled out by ¹⁹⁵Pt Knight-shift experiments. Furthermore an additional magnetic transition at 3 K and strong but slow magnetic fluctuations peaking at ∼ 120 K are detected by NMR. In addition to the magnetic probe investigations, we compare our results with transport measurements and specific heat studies.