Site-selective \(d^{10}\)/\(d^0\) substitution in a \(S = 1/2\) spin ladder Ba\(_2\)CuTe\(_{1-x}\)W\(_x\)O\(_6\) (\(0 \leq x \leq 0.3\))

Remarkably, doping isovalent \(d^{10}\) and \(d^0\) cations onto the \(B\)'' site in \(A_2B\)'\(B\)''O\(_6\) double perovskites has the power to direct the magnetic interactions between magnetic \(B\)' cations. This is due to changes in orbital hybridization, which favors different superexchange pathways, and leads to the formation of alternative magnetic structures depending on whether \(B\)'' is \(d^{10}\) or \(d^0\). Furthermore, the competition generated by introducing mixtures of \(d^{10}\) and \(d^0\) cations can drive the material into the realms of exotic quantum magnetism. Here, a W\(^{6+}\) \(d^0\) dopant was introduced to a \(d^{10}\) hexagonal perovskite Ba\(_2\)CuTeO\(_6\), which possesses a spin ladder geometry of Cu\(^{2+}\) cations, creating a Ba\(_2\)CuTe\(_{1-x}\)W\(_x\)O\(_6\) solid solution (\(x\) = 0 - 0.3). Neutron and synchrotron X-ray diffraction show that W\(^{6+}\) is almost exclusively substituted for Te\(^{6+}\) on the corner-sharing site within the spin ladder, in preference to the face-sharing site between ladders. This means the intra-ladder interactions are selectively tuned by the \(d^0\) cations. Bulk magnetic measurements suggest this suppresses magnetic ordering in a similar manner to that observed for the spin-liquid like material Sr\(_2\)CuTe\(_{1-x}\)W\(_x\)O\(_6\). This further demonstrates the utility of \(d^{10}\) and \(d^0\) dopants as a tool for tuning magnetic ground states in a wide range of perovskites and perovskite-derived structures.