Magnetic Excitations and Electronic Interactions in Sr 2 CuTeO 6 : A Spin- 1 / 2 Square Lattice Heisenberg Antiferromagnet

Abstract : Sr2CuTeO6 presents an opportunity for exploring low-dimensional magnetism on a square lattice of S ¼ 1=2 Cu2þ ions. We employ ab initio multireference configuration interaction calculations to unravel the Cu2þ electronic structure and to evaluate exchange interactions in Sr2CuTeO6. The latter results are validated by inelastic neutron scattering using linear spin-wave theory and series-expansion corrections for quantum effects to extract true coupling parameters. Using this methodology, which is quite general, we demonstrate that Sr2CuTeO6 is an almost ideal realization of a nearest-neighbor Heisenberg antiferromagnet but with relatively weak coupling of 7.18(5) meV.