Berlin 2018 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 65: Quantum-Critical Phenomena II
TT 65.2: Vortrag
Mittwoch, 14. März 2018, 15:15–15:30, HFT-FT 131
Investigation of magnetic fluctuations in the ferromagnet UGe2 by means of Modulated Intensity by Zero Effort (MIEZE) — •Franz Haslbeck1,2, Steffen Säubert1,3, Christian Franz3, Marc Janoschek2,4, and Christian Pfleiderer1 — 1TU Munich, Germany — 2Institute for Advanced Study, TU Munich, Germany — 3MLZ, TU Munich, Germany — 4LANL, USA
It is well known that the critical fluctuations associated with magnetic quantum critical points (QCP) are crucial for the emergence of novel states of matter such as unconventional superconductivity. However, their exact nature remains an outstanding question. Most notably, according to theory both the relaxation time and correlation length of the fluctuations are expected to diverge when the QCP is approached. However, to date this has not yet been observed, partially because this requires extreme energy and momentum transfer resolution. Here we show that for ferromagnetic QCPs this problem may be overcome using the newly developed longitudinal MIEZE (Modulated Intensity by Zero Effort) option at the instrument RESEDA at MLZ (Garching). To showcase the feasibility of this approach we have investigated the magnetic fluctuations in the material UGe2 at ambient pressure in a small angle scattering geometry. Our results demonstrate that this technique allows studying ferromagnetic critical fluctuations with an energy resolution that is almost two orders of magnitude higher than for classical triple axis spectroscopy while simultaneously providing access to small momentum transfers. In conclusion, this suggests that MIEZE may be used to obtain new insights in ferromagnetic QCPs.