Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 21: Superconductivity: Poster Session

TT 21.28: Poster

Montag, 16. März 2015, 15:00–18:00, Poster B

Superconducting properties and pseudogap from preformed Cooper pairs in the triclinic (CaFe1−xPtxAs)10Pt3As8 — •M. A. Surmach1, F. Brückner1, S. Kamusella1, R. Sarkar1, P. Y. Portnichenko1, J. T. Park2, G. Ghambashidze3, H. Luetkens4, P. Biswas4, W. J. Choi5, Y. I. Seo5, Y. S. Kwon5, H.-H. Klauss1, and D. S. Inosov11TU Dresden, Germany — 2MLZ, Garching, Germany — 3MPI, Stuttgart, Germany — 4PSI, Villigen, Switzerland — 5DGIST, Daegu, Republic of Korea

Using µSR, INS and NMR, we investigated the novel Fe-based superconductor with a triclinic crystal structure (CaFe1−xPtxAs)10Pt3As8 (Tc=13 K). The T-dependence of the superfluid density from the µSR measurements indicates the presence of two superconducting gaps. Our INS data revealed commensurate spin fluctuations at the (π, 0) wave vector. Their intensity remains unchanged across Tc, indicating the absence of a spin resonance typical for many Fe-pnictides. Instead, we observed a peak around ω0 = 7 meV at the same wave vector, which persists above Tc and is characterized by the ratio ω0/kBTc≈6.2, i.e. significantly higher than typical values for the magnetic resonant modes in iron pnictides (∼ 4.3). The T-dependence of magnetic intensity at 7 meV revealed an anomaly around T=45 K related to the disappearance of this new mode. A suppression of the spin-lattice relaxation rate, 1=/T1T, observed by NMR immediately below T without any notable subsequent anomaly at Tc, indicates that T could mark the onset of a pseudogap in (CaFe1−xPtxAs)10Pt3As8, likely associated with the emergence of preformed Cooper pairs.

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DPG-Physik > DPG-Verhandlungen > 2015 > Berlin