  Long range antiferromagnetic (AFM) ordering of Ni spins in Ni2NbBO6 has been
studied with single crystal from spin susceptibility measurement and
comparedwith the ab initio calculation results consistently. Below TN = 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) intrachain and interchain couplings of size half |J2|.
