Mechanism of Basal-Plane Antiferromagnetism in the Spin-Orbit Driven Iridate Ba2IrO4

作者:Katukuri Vamshi M*; Yushankhai Viktor; Siurakshina Liudmila; van den Brink Jeroen; Hozoi Liviu; Rousochatzakis Ioannis
来源:Physical Review X, 2014, 4(2): 021051.
DOI:10.1103/PhysRevX.4.021051

摘要

By ab initio many-body quantum chemistry calculations, we determine the strength of the symmetric anisotropy in the 5d(5) j approximate to 1/2 layered material Ba2IrO4. While the calculated anisotropic couplings come out in the range of a few meV, orders of magnitude stronger than in analogous 3d transition-metal compounds, the Heisenberg superexchange still defines the largest energy scale. The ab initio results reveal that individual layers of Ba2IrO4 provide a close realization of the quantum spin-1/2 Heisenberg-compass model on the square lattice. We show that the experimentally observed basal-plane antiferromagnetism can be accounted for by including additional interlayer interactions and the associated order-by-disorder quantum-mechanical effects, in analogy to undoped layered cuprates.