Frustrated magnetism of the spin-1 kagome antiferromagnet β-BaNi3(VO4)2(OH)2

Abstract

Abstract We propose the newly synthesized β-BaNi3(VO4)2(OH)2 (space group: R 3 ‾ m ) as a candidate for the spin-1 kagome Heisenberg antiferromagnet (KHA). The compound features a uniform kagome lattice of Ni2+ (S = 1) ions with a large interlayer distance. High-field measurements at low temperatures reveal a susceptibility local minimum at ∼9 T, resembling a 1/3 magnetization plateau as predicted by the pure S = 1 KHA model. Below ∼6 K, approximately 1% of the spins exhibit spin-glass order, which may be attributed to the nanocrystalline grain size of ∼50 nm. Despite the antiferromagnetic exchange coupling strength of ∼7 K, the majority of spins remain disordered down to ∼0.1 K as indicated by the observed power-law behaviors in magnetic specific heat C m ∝ T 1.4 . Our results demonstrate that the low-energy magnetic excitations in β-BaNi3(VO4)2(OH)2 are gapless, which contradicts the current theoretical expectations of the ideal model.