Regensburg 2016 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 19: Superconductivity: Poster Session

TT 19.23: Poster

Montag, 7. März 2016, 15:00–18:00, Poster D

Dynamic properties of Ca₁₀(Pt₃As₈)(Fe_1−xPt_xAs)₁₀ in the superconducting state explored by NMR in high fields — •Felix Brückner¹, Rajib Sarkar¹, Arneil P. Reyes², Philip L. Kuhns², Maksym Surmach¹, Dmytro Inosov¹, and Hans-Henning Klauss¹ — ¹Institut für Festkörperphysik, TU Dresden, Dresden, Germany — ²National High Magnetic Field Laboratory, Tallahassee, Florida, USA

The triclinic iron-based superconductor Ca₁₀(Pt₃As₈)(Fe_1−xPt_xAs)₁₀ with a T_c of 13 K exhibits a unique pseudogap phase below T^* = 45 K, recently probed with inelastic neutron scattering. This phase has been attributed to a possible preformation of Cooper pairs. We present detailed NMR results, including ⁷⁵As and ¹⁹⁵Pt spectra as well as T₁ measurements. These experiments reveal a drop of spin fluctuations just below T^* with a hysteresis in temperature, associated with the emergence of the pseudogap phase. Interestingly, no anomaly at T_c is found. At 3 K, a peak in the T₁ relaxation rate appears, until 1/T₁ eventually vanishes at lower temperatures. This behavior is persistent in large magnetic fields up to 17 T. To interpret these results, scenarios including magnetic order below T^* are quite unprobable, since Korringa law is well complied at higher temperatures and no magnetic order is found in µSR. However, the origin of the unique behavior remains unclear for now.