Eur. Phys. J. B 17, 609-614 (2000)
https://doi.org/10.1007/s100510070098

Antiferromagnetic resonance and high magnetic field properties of NaNiO₂

¹ Grenoble High Magnetic Field Laboratory, CNRS and MPI-FKF, BP 166X, 38042 Grenoble, France
² Laboratoire de Cristallographie, CNRS, BP 166X, 38042 Grenoble, France
³ Centre de Recherches sur les Très Basses Températures, CNRS, BP 166X, 38042 Grenoble, France

Received: 9 March 2000
Revised: 13 July 2000
Published online: 15 October 2000

Abstract

Magnetisation measurements up to 23 T and submillimeter wave ESR in the frequency region 48-380 GHz have been performed on NaNiO₂ powders at low temperature. Also typical spectra above the Néel temperature T_N are shown. At 4 K the magnetisation shows a spin-flop transition at 1.8 T and saturation at 10 T. /Ni confirms the low spin state of the Ni³⁺ ions. The susceptibility exhibits a maximum at K with and K. NaNiO₂ is an A-type antiferromagnet: we derive K and K for the interactions between Ni ions within and between adjacent layers, respectively. The AFMR spectra yield an energy gap of 52.5 GHz, in agreement with the spin-flop value derived from the magnetisation. The anisotropy of the g factor observed at 100 K with can be attributed to the Jahn-Teller effect for Ni³⁺ ions in the low spin state, which stabilises the occupation. We finally comment on the isomorphic controversial LiNiO₂ compound.