Berlin 2018 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 5: Heusler compounds, semimetals and oxides (joint session MA/TT)
MA 5.11: Vortrag
Montag, 12. März 2018, 12:15–12:30, EB 301
Anisotropy of the spin-fluctuations and its impact on the symmetry of the order parameter in the unconventional Sr2RuO4 superconductor. — S. Khmelevskyi1, B. Kim2, D. D. F. Agterberg3, P. Mohn1, •I. I. Mazin4, and C. Franchini2 — 1Center for Computational Materials Science, Vienna University of Technology, Vienna, Austria — 2Center for Computational Materials Physics, Vienna University, Vienna, Austria — 3University of Wisconsin, Milwaukee, USA. — 4Naval Research Laboratory, Washington DC, USA.
The superconductivity (SC) in the Sr2RuO4 has attracted a considerable interest in the past two decades comparable to that in cuprates and iron pnictides. NMR experiments strongly suggested a triplet chiral order parameter, while more recent probes of strained crystals point toward singlet pairing. In this work the structure of the spin-fluctuations in the Sr2RuO4 has been investigated from first principles using the DLM formalism and Lichtenstein method. We find that IC spin-fluctuations are stabilized but several magnetic ground states with q close to the commensurate (1/3, 1/3, 0) value are degenerate. We show that the degeneration is removed by Spin-orbit coupling and a very special collinear modulated magnetic structure with periodicity 1/3 is stabilized in the mean field in the [110] direction. We show that anisotropic magnetic terms provide an energy penalty for rotating the order parameter that is several orders of magnitude too large for the accepted interpretation, thus rendering the NMR experiment completely inexplicable in terms of the conventional theory.