Unconventional magnetic ground state in Yb sub(2)Ti sub(2)O sub(7)

We report low-temperature specific heat and positive muon spin relaxation/rotation ( mu SR) measurements on both polycrystalline and single-crystal samples of the pyrochlore magnet Yb sub(2) Ti sub(2) O sub(7). This material is believed to possess a spin Hamiltonian able to support a quantum spin ic...

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Bibliographic Details
Published in:Physical review. B, Condensed matter and materials physics Condensed matter and materials physics, 2013-10, Vol.88 (13)
Main Authors: D'Ortenzio, R M, Dabkowska, H A, Dunsiger, S R, Gaulin, B D, Gingras, M J P, Goko, T, Kycia, J B, Liu, L, Medina, T, Munsie, T J, Pomaranski, D, Ross, K A, Uemura, Y J, Williams, T J, Luke, G M
Format: Article
Language:English
Subjects:
Condensed matter
Ferromagnetism
Ground state
Heat capacity
Muon spin relaxation
Muons
Specific heat
Temperature dependence
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Summary:We report low-temperature specific heat and positive muon spin relaxation/rotation ( mu SR) measurements on both polycrystalline and single-crystal samples of the pyrochlore magnet Yb sub(2) Ti sub(2) O sub(7). This material is believed to possess a spin Hamiltonian able to support a quantum spin ice (QSI) ground state. Yb sub(2) Ti sub(2) O sub(7) displays sample variation in its low-temperature heat capacity and, while our two samples exhibit extremes of this variation, our mu SR measurements indicate a similar disordered low-temperature state down to 16 mK in both. We report little temperature dependence to the muon spin relaxation and no evidence for ferromagnetic order, in contrast to reports by Chang et al. [Nat. Comm. 3, 992 (2012) (http://dx.doi.org/10.1038/ncomms1989)] and Yasui et al. [J. Phys. Soc. Japan. 72, 11 (2003)]. Transverse field (TF) mu SR measurements show changes in the temperature dependence of the muon Knight shift that coincide with heat capacity anomalies, which, incidentally, prove that the implanted muons are not diffusing in Yb sub(2) Ti sub(2) O sub(7). From these results, we are led to propose that Yb sub(2) Ti sub(2) O sub(7) enters an unconventional ground state below T sub(c) ~ 265 mK. As found for all the current leading experimental candidates for a quantum spin liquid state, the precise nature of the state below T sub(c) in Yb sub(2) Ti sub(2) O sub(7) remains unknown and, at this time, defined by what is not as opposed to what it is: lacking simple periodic long-range order or a frozen spin glass state.
ISSN:1098-0121
1550-235X