Coexisting long-range zigzag antiferromagnetic order and glassy dynamics in spin-1 honeycomb lattice Na3Ni2SbO6

Abstract

Here, we report an interesting magnetic oxide Na 3Ni 2SbO 6, where the interplay between exchange interactions and lattice symmetry crucially influence its exotic ground state (GS). This compound features a layered honeycomb lattice with magnetic Ni 2+ (spin-1) surrounding nonmagnetic Sb 5+ centers. The x-ray absorption and magnetic circular dichroism measurements confirm a Ni 2+ charge state with notable spin and orbital moments at room temperature. The material exhibits antiferromagnetic (AFM) ordering around 17 K ( TN) and a field-induced magnetic transition at lower temperatures. Our measurements reveal a low-temperature anomaly, likely linked to glassy behavior. The power-law magnetic specific heat suggests mixed magnon dispersion, while low magnetic entropy indicates a highly degenerate GS. Neutron diffraction data point to a zigzag-type AFM GS, with a reduced site moment of 1.34(3) μB/Ni2+ at 2.5 K that disappears near 17.2 K, consistent with bulk data. Lattice parameters show anomalies at TN and lower temperatures. Ab-initio calculations support zigzag spin order and imply a competing in-plane Ni 2+ interactions that causes spin frustration. Overall, our combined experimental and theoretical study uncovers the microscopic magnetic GS of Na 3Ni 2SbO 6 as a mix of long-range zigzag AFM and a glassy state, advancing the understanding of frustrated honeycomb magnets.