Berlin 2018 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 72: Poster Session: Correlated Electrons
TT 72.38: Poster
Mittwoch, 14. März 2018, 15:00–19:00, Poster B
Persistent spin dynamics in NaCaCo2F7 as evidenced by µSR — •Sascha Albert Bräuninger1, Rajib Sarkar1, Jason W. Krizan2, Philip Materne1, Chris Baines3, Hubertus Luetkens3, Robert J. Cava2, and Hans-Henning Klauss1 — 1Institute of Solid State and Materials Physics, TU Dresden, D-01069, Germany — 2Department of Chemistry, Princeton University, Princeton, NJ 08544, USA — 3Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
The fluoride pyrochlore NaCaCo2F7 is a newly discovered frustrated pyrochlore with a frustration index of f = |θCW|/Tf≈ 56. While recent NMR experiments on NaCaCo2F7 suggested a spin frozen state below 3 K, neutron scattering experiments on the other hand proposed XY like antiferromagnetic spin clusters at low energies. We present µSR studies on NaCaCo2F7. Present results indicate the slowing down of the magnetic spin fluctuation upon cooling towards the NMR and neutron scattering spin frozen state transition temperature of Tsf≈ 3.0 K. The µSR relaxation rate increases slightly below this frozen state, and remains constant down to 20 mK. In the µSR window there is no indication of static magnetism in NaCaCo2F7. In longitudinal field (100-4000 G) the relaxation rate do not vary indicating that the spin fluctuations are dynamic, and this is persistent even at T≈ 20 mK. While persistent spin dynamics (PSD) appears to be a generic feature of frustrated magnetic systems, it is not clear so far for the present case whether this is associated with quantum fluctuations, spin-liquid physics, or some other effect.