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TT: Fachverband Tiefe Temperaturen
TT 34: Correlated Electrons: Frustrated Magnets - Chiral Magnets & RuCl3
TT 34.3: Talk
Tuesday, March 8, 2016, 14:30–14:45, H20
The microscopic NMR probe in chiral magnets: zero field-, field-modulated- and Skyrmion- states in FeGe and MnSi — •Michael Baenitz1, Hiroshi Yasuoka1, Mayukh Majumder1, Panchanan Khuntia1, Sebastian Witt2, Cornelius Krellner2, and Markus Schmidt1 — 1MPI for the Chemical Physics of Solids, 01187 Dresden, Germany — 2Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
Cubic FeGe is a prototype B20 chiral magnet (Tc = 280 K) which allows to study chiral correlations directly "on-site" via the57Fe nucleus because of its S=1/2 nuclear spin interacting only with the electron spin moment. NMR provides the static and dynamic staggered local magnetization MQ through the hyperfine field (Hhf) and the spin lattice relaxation rate (SLRR = 1/T1). Measurements were performed on randomly oriented 57Fe enriched FeGe single crystals between 2-300 K. Helical- , conical- and field-polarized-states could be clearly identified and spin dynamics of each phase was investigated. MnSi single crystals and 29Si enriched MnSi polycrystals were studied by 29Si-NMR (S=1/2) in the ordered state (Tc = 29 K) and above. The T- and H- dependence of Hhf and SLRR was investigated in great detail for both FeGe and MnSi.The 29Si-NMR lines in MnSi are narrow and Hhf-values obtained are smaller than in FeGe. Our results are in general accordance with the extended SCR theory for itinerant helical magnets [1], although the theory does not include the symmetry breaking in the B20 structure and the multi-band nature. For FeGe correlations are complex due to its more localized magnetism.
[1] T. Moriya, J. Phys. Soc. Jpn. 40, 933 (1976)