Tight-Binding Approach to Pyrazine-Mediated Superexchange in Copper–Pyrazine Antiferromagnets

We investigate the cause of spatial superexchange anisotropy in a family copper-based, quasi-two-dimensional materials with very similar geometries. The compounds this differ mainly their inter-layer separation but they have different magnetic interactions, even within basal plane. use density functional theory and Wannier functions to parameterize two complimentary tight-binding models show that between Cu2+ ions is dominated by ?-mediated interaction hybrid Cu–pyrazine orbitals centered on copper atoms. find no correlations strength exchange homologous geometric features across compounds, such as Cu pyrazine bond lengths orientations nearby counterions. tilt angles do not affect Cu–pyrazine–Cu because lowest unoccupied molecular orbital at high energy (relative frontier orbitals, which are Cu-based). conclude careful control entire crystal structure, including non-homologous organic ligands, vital for engineering properties.