Dresden 2009 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 14: Poster Ib: Magnetic Materials (1-14); Micro Magnetism/Computational Mag. (15-17); Surface Magnetism (18-22); Spin Structures/Phase Transitions (23-25)
MA 14.23: Poster
Dienstag, 24. März 2009, 10:15–13:00, P1B
Domain Effects, Giant Magnetoresistance and Quantum Phase Transitions in NbFe2 — •William Duncan1, Philipp Niklowitz1, Carsten Albrecht1, Dennis Moroni1, Manuel Brando2, and Malte Grosche3 — 1Department of Physics, Royal Holloway, Egham, TW20 0EX, UK — 2Max-Planck-Institute CPfS, 01187 Dresden, Germany — 3Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK
The C14 Laves phase NbFe2 offers an intriguing perspective on ferromagnetic quantum criticality in clean transition metal compounds. Slightly (1%) iron-rich samples of NbFe2 are low-temperature band ferromagnets. On approaching stoichiometry, an unidentified modulated magnetic state with a high uniform susceptibility (Stoner enhancement factor ~ 150) replaces ferromagnetism. This modulated, possibly long-wavelength spiral order eventually disappears in slightly niobium-rich samples, giving rise to a quantum critical point (QCP).
Numerous polycrystals of varying stoichiometries have been prepared and their respective magnetic and transport properties have been investigated. There are several intriguing phenomena present, these include quantum critical behaviour near the QCP (see other poster, [1]), GMR approaching 40% coupled with strong domain effects near the region of the ferromagnetic to modulated state change and robust non-Fermi liquid behaviour. Hydrostatic pressure has been used to reproduce the effects of changing composition, suggesting that disorder and impurity effects play a minor role in doped samples.
[1] M. Brando et al, Phys. Rev. Lett. 101, 026401 (2008)