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TT: Fachverband Tiefe Temperaturen
TT 4: CE: Quantum-Critical Phenomena 1
TT 4.2: Talk
Monday, March 14, 2011, 10:45–11:00, HSZ 201
Quantum Phase Transitions in Mn1−xFexSi and Mn1−xCoxSi — •Andreas Bauer1, Tim Adams1, Christian Franz1, Andreas Neubauer1, Maximilian Hirschberger1, Christopher Krey1, Robert Georgii1,2, Peter Böni1,2, Markus Garst1,3, and Christian Pfleiderer1 — 1Physik Department E21/T30, Technische Universität München, Germany — 2Forschungsneutronenquelle Heinz Maier-Leibnitz, Technische Universität München, Germany — 3Institute for Theoretical Physics, Universität zu Köln, Germany
The helimagnetic order in MnSi may be suppressed by substitutional doping of Fe or Co on the Mn site. We report a comprehensive study of the magnetization, susceptibility, specific heat and small angle neutron scattering of single-crystal Mn1−xFexSi and Mn1−xCoxSi at low temperatures [1]. In contrast to the pressure dependence of pure MnSi the spin polarized state in applied magnetic fields is characteristic of a putative ferromagnetic quantum critical point at a critical concentration xc. The magnetic phase diagram as a function of composition up to x ≈ 0.5 xc is thereby essentially unchanged, exhibiting the well known phases (helical order, conical order, and skyrmion lattice phase [2]). When further increasing x the regime of the skyrmion lattice and the cross-over between the paramagnetic and the helimagnetic state, which may be related to complex spin textures, extend over an increasing temperature and field range. This points at an important role of complex spin textures in the vicinity of xc.
A. Bauer et al., PRB 82, 064404 (2010)
S. Mühlbauer et al., Science 323, 915 (2009)