Dresden 2017 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 13: Superconductivity: Fe-based Superconductors - 122

TT 13.11: Vortrag

Montag, 20. März 2017, 17:45–18:00, HSZ 103

Impurity effects on spin dynamics in Ba(Fe_1−xMn_x)₂As₂ (x = 12 %) — •M. A. Surmach¹, P. Y. Portnichenko¹, J. T. Park², J. A. Rodriguez-Rivera^3,4, D. L. Sun⁵, Y. Liu⁵, C. T. Lin⁵, and D. S. Inosov¹ — ¹Institut fur Festkörperphysik, TU Dresden, Germany — ²MLZ, TU München, Garching, Germany — ³Materials Science and Engineering, University of Maryland, USA — ⁴NIST Center for Neutron Research, Gaithersburg, USA — ⁵MPI fur Festkörperforschung, Stuttgart, Germany

We present new results on the structure of magnetic fluctuations in BaFe₂As₂ single crystals doped with Mn local moments and discuss them in relationship to the previously reported (π, π) branch of checkerboard magnetic excitations.

Mn doping introduces strong magnetic impurities, which abruptly suppress superconductivity in Fe-based compounds and evoke the second branch of diffuse short-range spin fluctuations near the (π, π) wave vector, in contrast to other iron-based superconductors, where fluctuations are limited to (π, 0) and (0, π) nesting vectors.

Our neutron spectrscopy measurements reveal the true momentum and energy dependence of the (π, π) branch of magnetic excitations along the out-of-plane (π π L) direction. We firstly showed strong three-dimensional character of these spin fluctuations, in contrast to other iron-based systems. We also report the presence of the low temperature partial spin gap along the (π π L) direction, which gradually opens below 7 meV.