μsR study of spin freezing and persistent spin dynamics in NaCaNi2F7 Academic Article uri icon

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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 ($\mu$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-$\mu$-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.

authors

  • Cai, Y
  • Wilson, MN
  • Hallas, AM
  • Liu, L
  • Frandsen, BA
  • Dunsiger, SR
  • Krizan, JW
  • Cava, RJ
  • Rubel, Oleg
  • Uemura, YJ
  • Luke, Graeme

publication date

  • August 29, 2018