Dresden 2014 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

MA: Fachverband Magnetismus

MA 15: Spin structures and Magnetic Phase Transitions

MA 15.1: Vortrag

Dienstag, 1. April 2014, 09:30–09:45, HSZ 403

The prototype chiral ferromagnet FeGe: phase diagram, Skyrmions and ⁵⁷Fe magnetic resonance — •Michael Baenitz¹, Panchanan Khuntia¹, Markus Schmidt¹, Ulrich Roessler², and Heribert Wilhelm³ — ¹MPI for the Chemical Physics of Solids, 01187Dresden, Germany — ²Leibniz Institute for SolidState and Materials Research, 01171 Dresden, Germany — ³Diamond Light Source Ltd, Didcot, Oxfordshire,United Kingdom

The helical ferromagnet FeGe belongs to the class of B20 compounds with non-centrosymmetric structure being essential for new forms of ferromagnetic phases (confined or modulated Skyrmion phases). From an NMR point FeGe is a prototype system to study chiral excitations directly "on-site" via the ⁵⁷Fe nucleus because of its S=1/2 nuclear spin. Here, in contrast to MnSi or MnGe (where ⁵⁵Mn has S=5/2), the absence of quadrupolar interactions, which usually creates broad NMR lines, makes detailed investigations of the anisotropic Zeeman interaction in internal/external fields possible. ⁵⁷Fe NMR allows to probe the local susceptibility (hyperfine field), the dynamic susceptibility (spin lattice relaxation rate) and the spin-spin interaction directly "on site". Additionally the NMR line itself (its Fourier transform) provides information about the multiplicity of the Fe sites in the complex helimagnet. ⁵⁷Fe NMR was performed on crushed single crystals of ⁵⁷Fe enriched FeGe material between 2-300 K in zero and applied magnetic fields. Phase boundaries in the ordered state are identified and critical dynamics in the vicinity of these boundaries are obtained from the spin-lattice and spin-spin relaxation rate.