  An elastic neutron scattering study has been performed on several single
crystals of La$_{2-x}$Sr$_{x}$CuO$_{4}$ for {\it x} near the lower critical
concentration {\it x$_{c}$} for superconductivity. % In the insulating
spin-glass phase ({\it x} = 0.04 and 0.053), the previously reported
one-dimensional spin modulation along the orthorhombic {\it b}-axis is
confirmed. % Just inside the superconducting phase ({\it x} = 0.06), however,
two pairs of incommensurate magnetic peaks are additionally observed
corresponding to the spin modulation parallel to the tetragonal axes. % These
two types of spin modulations with similar incommensurabilities coexist near
the boundary. % The peak-width $\kappa$ along spin-modulation direction
exhibits an anomalous maximum in the superconducting phase near {\it x$_{c}$},
where the incommensurability $\delta$ monotonically increases upon doping
across the phase boundary. % These results are discussed in connection with the
doping-induced superconducting phase transition.
