Berlin 2018 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 60: Focus Session: Topological Defects in Superconductors and Magnets (joint session TT/MA)
TT 60.4: Hauptvortrag
Mittwoch, 14. März 2018, 16:45–17:15, H 0104
Hedgehog Spin-Vortex Crystal Magnetic Order in Superconducting CaK(Fe1−xMx)4As4 (M=Co, Ni) — •Anna Böhmer — Ames Laboratory, Iowa, USA — IFP, Karlsruhe Institute of Technology, Germany
Iron-based superconductors can support a number of antiferromagnetic phases, of which stripe-type antiferromagnetism is most common. It is found that Ni- and Co-doping in CaKFe4As4 suppresses superconductivity and stabilizes a new antiferromagnetic phase. This phase is studied using thermodynamic, transport, x-ray and neutron diffraction, as well as local magnetic measurements. A non-collinear antiferromagnetic structure preserving tetragonal symmetry is revealed. It is characterized by a superposition of the propagation vectors of the common stripe-type antiferromagnetism. This antiferromagnetic structure with a "hedgehog-type" moment motif is stabilized by the reduced symmetry of the CaKFe4As4 structure.
This work was performed in collaboration with W. R. Meier, Q.-P. Ding, A. Kreyssig, M. Xu, S. L. Bud’ko, A. Sapkota, K. Kothapalli, J. M. Wilde, W. Tian, V. Borisov, R. Valentí, C. D. Batista, P. P. Orth, R. M. Fernandes, R. J. McQueeney, A. I. Goldman, Y. Furukawa and P. C. Canfield and supported by the Gordon and Betty Moore Foundation’s EPiQS Initiative through Grant GBMF4411 and the US DOE, Basic Energy Sciences under Contract No. DE-AC02-07CH11358.
W. R. Meier et al., arXiv:1706.01067 (2017).