Static and dynamic spin correlations in the spin-glass phase of slightly doped La2-xSrxCuO4

Neutron-scattering experiments reveal that a diagonal spin modulation, whic h is a one-dimensional modulation rotated away by 45 degrees from that in t he superconducting phase, occurs universally across the insulating spin-gla ss phase in La2-xSrxCuO4 (0.02 less than or equal to x less than or equal t o 0.055). This establishes an intimate relation between the magnetism and t he transport properties in the high-temperature copper oxide superconductor s. Furthermore, it is found that the charge density per unit length estimat ed using a charge stripe model is almost constant throughout the phase diag ram, even when the modulation rotates away by 45 degrees at the superconduc ting boundary. However. at the lowest values for I the density changes appr oaching 1 hole/Cu as in La2-xSrxNiO4. Magnetic excitation spectra suggest t hat magnetic correlations change from incommensurate to commensurate at ome ga similar to 7 meV and T similar to 70 K, indicating a characteristic ener gy for the incommensurate structure of 6-7 meV.