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$��$SR study of spin freezing and persistent spin dynamics in NaCaNi$_2$F$_7$

Authors :
Cai, Y.
Wilson, M. N.
Hallas, A. M.
Liu, L.
Frandsen, B. A.
Dunsiger, S. R.
Krizan, J. W.
Cava, R. J.
Uemura, Y. J.
Rubel, O.
Luke, G. M.
Publication Year :
2018
Publisher :
arXiv, 2018.

Abstract

A new pyrochlore compound, NaCaNi$_2$F$_7$, was recently synthesized and has a single magnetic site with spin-1 Ni$^{2+}$. We present zero field (ZF) and longitudinal field (LF) muon spin rotation ($��$SR) measurements on this pyrochlore. Density functional theory (DFT) calculations show that the most likely muon site is located between two fluorine ions, but off-centre. A characteristic F-$��$-F muon spin polarization function is observed at high temperatures where Ni spin fluctuations are sufficiently rapid. The Ni$^{2+}$ 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.

Details

Database :
OpenAIRE
Accession number :
edsair.doi...........d9ee0b4a48d77ea116b2e7c69174d2f7
Full Text :
https://doi.org/10.48550/arxiv.1806.10970