Correlations between charge ordering and local magnetic fields in overdoped YBa 2 Cu 3 O 6 + x

Zero-field muon spin-relaxation $(\mathrm{ZF}\ensuremath{-}\ensuremath{\mu}\mathrm{SR})$ measurements were undertaken on under- and overdoped samples of superconducting ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{6+x}$ to determine the origin of the weak static magnetism recently reported in this system. The temperature dependence of the muon spin-relaxation rate in overdoped crystals displays an unusual behavior in the superconducting state. A comparison to the results of NQR and lattice structure experiments on highly doped samples provides compelling evidence for strong coupling of charge, spin, and structural inhomogeneities.