Regensburg 2010 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 22: CE: Spin Systems and Itinerant Magnets
TT 22.11: Vortrag
Mittwoch, 24. März 2010, 12:15–12:30, H21
Quantum Phase Transitions in Single-Crystal Mn1−xFexSi and Mn1−xCoxSi: III. Magnetoresistance and Hall effect — •Christian Franz — Physik Department E21, Technische Universität München, München, Germany
Complex spin textures with non-trivial topology may generate anomalous contributions in the Hall conductivity, the so-called topological Hall effect, that provide direct evidence of non-vanishing winding numbers. We report a comprehensive study of the evolution of the spin structures and spin textures in Mn1−xFexSi and Mn1−xCoxSi by means of the magnetoresistance and the Hall effect. Our study identifies the A-phase, located just below the helimagnetic transition, as a sykrmion lattice for a wide range of x. Combining the bulk properties and small angle neutron scattering with our Hall effect data additionally suggests the formation of non-trivial spin textures in parameter regimes outside the A phase when approaching quantum criticality under Fe- and Co-doping. Similarities and differences with pure MnSi and the doped semiconductor Fe1−xCoxSi will be discussed.