Static vacancies in antiferromagnetic ${\mathrm{La}}_2$${\mathrm{CuO}}_4$ and superconducting ${\mathrm{La}}_{2\mathrm{-}\mathit{x}}$${\mathrm{Sr}}_{\mathit{x}}$${\mathrm{CuO}}_4$

The effect of static vacancies that eliminate local ${\mathrm{Cu}}^{2+}$ spins has been studied in both the antiferromagnetic and superconducting state of ${\mathrm{La}}_{2\mathrm{-}\mathit{x}}$ ${\mathrm{Sr}}_{\mathit{x}}$ ${\mathrm{CuO}}_4$. Static vacancies induce uncompensated magnetic moments and suppress the three-dimensional Néel state much less effectively than mobile vacancies. Analysis of magnetic susceptibility provides accurately the ${\mathrm{Cu}}^{2+}$ magnetic moment (∼1${\mathrm{\mu }}_{\mathit{B}}$), which is insensitive to Sr doping, indicating that the d state of ${\mathrm{Cu}}^{2+}$ remains highly localized upon the introduction of mobile vacancy.