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

TL;DR

This study investigates the antiferromagnetic properties of Ni2NbBO6, revealing long-range order below 23.5 K, spin anisotropy along the a axis, and the role of S=1 dimers in its quasi-one-dimensional armchair chain structure, supported by experimental and theoretical analysis.

Contribution

It provides a combined experimental and theoretical analysis of the antiferromagnetic order and spin structure in Ni2NbBO6, highlighting the role of S=1 dimers and armchair chains, which is novel in this context.

Findings

Long-range AFM order below 23.5 K confirmed.

Spin-flop transition observed at 36 kOe along a axis.

Theoretical calculations support experimental AFM structure.

Abstract

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|.