Anisotropic magnetic couplings and structure-driven canted to collinear transitions in Sr2IrO4 by magnetically constrained noncollinear DFT

摘要: We study the canted magnetic state in Sr2IrO4 using fully relativistic density functional theory (DFT) including an on-site Hubbard U correction. A complete phase diagram with respect to tetragonal distortion and rotation of IrO6 octahedra is constructed, revealing presence two types collinear transitions: a spin-flop transition increasing quenching basal weak ferromagnetic moment below critical octahedral rotation. Moreover, we put forward scheme anisotropic couplings by mapping magnetically constrained noncollinear DFT onto general spin Hamiltonian. This procedure allows for simultaneous account direct control lattice, spin, orbital interactions within ab initio scheme. compute isotropic, single site anisotropy Dzyaloshinskii-Moriya (DM) coupling parameters, clarify that origin arises from structural distortions competition between isotropic exchange DM interactions.