Low-energy spin dynamics in a Kitaev material Na3Ni2BiO6 investigated by NMR

Abstract

We performed 23Na NMR and magnetization measurements on an S = 1, quasi-2D honeycomb lattice antiferromagnet Na3Ni2BiO6. A large positive Curie-Weiss constant of 22.9 K is observed. The NMR spectra at low fields are consistent with a "zigzag" magnetic order, indicating a large easy-axis anisotropy. With field applied along the c* axis, the NMR spectra confirm the existence of a 1/3-magnetization plateau phase between 5.1 T and 7.1 T. The transition from the zigzag order to the 1/3-magnetization plateau phase is also found to be a first-order type. A monotonic decrease of the spin gap is revealed in the 1/3-magnetization plateau phase, which reaches zero at a quantum critical field Hc = 8.35 T before entering the fully polarized phase. These data suggest the existence of exchange frustration in the system along with strong ferromagnetic interactions, hosting the possibility for Kitaev physics. Besides, well below the ordered phase, the 1/T1 at high fields shows either a level off or an enhancement upon cooling below 3 K, which suggests the existence of low-energy fluctuations.

7 pages, 7 figures

References in corpus (19)

• Mott Insulators in the Strong Spin-Orbit Coupling Limit: From Heisenberg to a Quantum Compass and Kitaev Models
• Magnetic order in $\alpha$-RuCl${}_3$: a honeycomb lattice quantum magnet with strong spin-orbit coupling
• Long range magnetic ordering in Na${}_2$IrO${}_3$
• Unusual ordered phases of highly frustrated magnets: a review
• Magnetic Excitations and Continuum of a Field-Induced Quantum Spin Liquid in $\alpha$-RuCl${}_3$
• Field-induced quantum spin disordered state in spin-1/2 honeycomb magnet Na2Co2TeO6
• Magnetic properties of the honeycomb oxide Na${}_2$Co${}_2$TeO${}_6$
• Zigzag antiferromagnetic ground state with anisotropic correlation lengths in the quasi-2D honeycomb lattice compound Na2Co2TeO6
• Antiferromagnetic Kitaev interaction in $J_\rm{eff}=1/2$ cobalt honeycomb materials Na${}_3$Co${}_2$SbO${}_6$ and Na${}_2$Co${}_2$TeO${}_6$
• Quantum stabilization of 1/3-magnetization plateau in Cs_2CuBr_4
• Magnetic order in single crystals of Na3Co2SbO6 with a honeycomb arrangement of 3d${}^7$ Co${}^{2+}$ ions
• Spin nematics and magnetization plateau transition in anisotropic Kagome magnets
• Identification of Magnetic Interactions and High-field Quantum Spin Liquid in $\alpha$-RuCl${}_3$
• Giant magnetic in-plane anisotropy and competing instabilities in Na3Co2SbO6
• Thermodynamics of the Up-Up-Down Phase of the S = 1/2 Triangular-Lattice Antiferromagnet Cs${}_2$CuBr${}_4$
• Observation of a 1/3 Magnetisation Plateau Phase as Evidence for the Kitaev Interaction in a Honeycomb-Lattice Antiferromagnet
• Quantum paramagnetism and magnetization plateaus in a kagome-honeycomb Heisenberg antiferromagnet
• Field-induced phase transitions and quantum criticality in a honeycomb antiferromagnet Na3Co2SbO6
• Nematicity and fractional magnetization plateaus induced by spin-lattice coupling in the classical kagome-lattice Heisenberg antiferromagnet