  We have performed muon spin relaxation and low field ac-susceptibility
measurements in a series of high quality samples of La_{2-x}Sr_xCuO_4
(x=0.08-0.24) as a function of temperature. Superconductivity is found to
coexist with low temperature spin glass order up to the optimally doped region
where the normal state pseudogap also closes. The systematic depletion of the
superfluid density with the enhancement of aniferromagnetic correlations with
underdoping indicates a competition between antiferromagnetic correlations and
superconductivity.
