From spin glass to quantum spin liquid ground states in molybdate pyrochlores

We present new magnetic heat capacity and neutron scattering results for two magnetically frustrated molybdate pyrochlores: S=1 oxide Lu_{2}Mo_{2}O_{7} and S=1/2 oxynitride Lu_{2}Mo_{2}O_{5}N_{2}. Lu_{2}Mo_{2}O_{7} undergoes a transition to an unconventional spin glass ground state at T_{f}∼16  K. H...

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Bibliographic Details
Published in:Physical review letters 2014-09, Vol.113 (11), p.117201-117201, Article 117201
Main Authors: Clark, L, Nilsen, G J, Kermarrec, E, Ehlers, G, Knight, K S, Harrison, A, Attfield, J P, Gaulin, B D
Format: Article
Language:English
Subjects:
Estimates
Ground state
Molybdates
Oxides
Oxynitrides
Physics
Pyrochlores
Spin glass
Spin liquid
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Summary:We present new magnetic heat capacity and neutron scattering results for two magnetically frustrated molybdate pyrochlores: S=1 oxide Lu_{2}Mo_{2}O_{7} and S=1/2 oxynitride Lu_{2}Mo_{2}O_{5}N_{2}. Lu_{2}Mo_{2}O_{7} undergoes a transition to an unconventional spin glass ground state at T_{f}∼16  K. However, the preparation of the corresponding oxynitride tunes the nature of the ground state from spin glass to quantum spin liquid. The comparison of the static and dynamic spin correlations within the oxide and oxynitride phases presented here reveals the crucial role played by quantum fluctuations in the selection of a ground state. Furthermore, we estimate an upper limit for a gap in the spin excitation spectrum of the quantum spin liquid state of the oxynitride of Δ∼0.05  meV or Δ/|θ|∼0.004, in units of its antiferromagnetic Weiss constant θ∼-121  K.
ISSN:0031-9007
1079-7114
DOI:10.1103/physrevlett.113.117201