Hybridization and spin-orbit coupling effects in the quasi-one-dimensional spin- 12 magnet Ba3Cu3Sc4O12

Abstract

We study electronic and magnetic properties of the quasi-one-dimensional spin-12 magnet Ba3Cu3Sc4O12 with a distinct orthogonal connectivity of CuO4 plaquettes. An effective low-energy model taking into account spin-orbit coupling was constructed by means of first-principles calculations. On this basis, a complete microscopic magnetic model of Ba3Cu3Sc4O12, including symmetric and antisymmetric anisotropic exchange interactions, is derived. The anisotropic exchanges are obtained from a distinct first-principles numerical scheme combining, on one hand, the local density approximation taking into account spin-orbit coupling, and, on the other hand, a projection procedure along with the microscopic theory by Moriya [Phys. Rev. 120, 91 (1960)PHRVAO0031-899X10.1103/PhysRev.120.91]. The resulting tensors of the symmetric anisotropy favor collinear magnetic order along the structural chains with the leading ferromagnetic coupling J1≃-9.88 meV. The interchain interactions J8≃0.21 and J5≃0.093 meV are antiferromagnetic. Quantum Monte Carlo simulations demonstrate that the proposed model reproduces the experimental Neel temperature, magnetization, and magnetic susceptibility data. The modeling of neutron-diffraction data reveals an important role of the covalent Cu-O bonding in Ba3Cu3Sc4O12. © 2016 American Physical Society.