Magnetic Excitations and Electronic Interactions inSr2CuTeO6: A Spin-1/2Square Lattice Heisenberg Antiferromagnet

Abstract

${\mathrm{Sr}}_2{\mathrm{CuTeO}}_6$ presents an opportunity for exploring low-dimensional magnetism on a square lattice of $S=1/2{\mathrm{Cu}}^{2+}$ ions. We employ ab initio multireference configuration interaction calculations to unravel the ${\mathrm{Cu}}^{2+}$ electronic structure and to evaluate exchange interactions in ${\mathrm{Sr}}_2{\mathrm{CuTeO}}_6$. 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 ${\mathrm{Sr}}_2{\mathrm{CuTeO}}_6$ is an almost ideal realization of a nearest-neighbor Heisenberg antiferromagnet but with relatively weak coupling of 7.18(5) meV.