μSR study of spin freezing and persistent spin dynamics in NaCaNi2F7

A new pyrochlore compound, NaCaNi2F7, was recently synthesized and has a single magnetic site with spin-1 Ni2+ . We present zero field and longitudinal field muon spin rotation (μSR) measurements on this pyrochlore. Density functional theory calculations show that the most likely muon site is locate...

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Bibliographic Details
Published in:Journal of physics. Condensed matter 2018-09, Vol.30 (38), p.385802-385802
Main Authors: Cai, Y, Wilson, M N, Hallas, A M, Liu, L, Frandsen, B A, Dunsiger, S R, Krizan, J W, Cava, R J, Rubel, O, Uemura, Y J, Luke, G M
Format: Article
Language:English
Subjects:
frustrated magnetic
NaCaNi
pyrochlore
spin dynamics
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Summary:A new pyrochlore compound, NaCaNi2F7, was recently synthesized and has a single magnetic site with spin-1 Ni2+ . We present zero field and longitudinal field muon spin rotation (μSR) measurements on this pyrochlore. Density functional theory calculations show that the most likely muon site is located between two fluorine ions, but off-centre. A characteristic F-μ-F muon spin polarization function is observed at high temperatures where Ni spin fluctuations are sufficiently rapid. The Ni2+ spins undergo spin freezing into a disordered ground state below 4 K, with a characteristic internal field strength of 140 G. Persistent Ni spin dynamics are present to our lowest temperatures (75 mK), a feature characteristic of many geometrically frustrated magnetic systems.
ISSN:0953-8984
1361-648X
DOI:10.1088/1361-648X/aad91c