Antiferromagnetism of Ni2NbBO6 with S = 1 dimer quasi-one-dimensional armchair chains

Abstract

Long range antiferromagnetic (AFM) ordering of Ni spins in Ni2NbBO6 has been studied with single crystal from spin susceptibility measurement and compared with the ab initio calculation results consistently. Below T N∼23.5 K, the S = 1 spins align along the a-direction for edge-shared NiO6 octahedra which form crystallographic armchair chains along the b-direction. The isothermal magnetization M (H) below TN shows spin-flop transition for magnetic field above ∼ 36 kOe along the a-axis, which indicates the spin anisotropy is along the a-direction. The electronic and magnetic structures of Ni2NbBO6 have also been explored theoretically using density functional theory with generalized gradient approximation plus on-site Coulomb interaction (U). These calculations support the experimentally observed antiferromagnetism of Ni2NbBO6. In particular, the long range AFM ordering below TN can be dissected into armchair chains which consists of S = 1 dimers of J2∼2.43 meV with ferromagnetic (FM) intra-chain and inter-chain couplings of size 1 2 |J2|.