  We explore the magnetically-ordered ground state of the
isovalently-substituted Mott-insulator Y$_{1-x}$La$_{x}$TiO$_{3}$ for $x$
$\leq$ 0.3 via single crystal growth, magnetometry, neutron diffraction, x-ray
magnetic circular dichroism (XMCD), muon spin rotation ($\mu$SR) and
small-angle neutron scattering (SANS). We find that the decrease in the
magnetic transition temperature on approaching the ferromagnetic (FM) -
antiferromagnetic (AFM) phase boundary at the La concentration $x_c$ $\approx$
0.3 is accompanied by a strong suppression of both bulk and local ordered
magnetic moments, along with a volume-wise separation into magnetically-ordered
and paramagnetic regions. The thermal phase transition does not show
conventional second-order behavior, since neither a clear signature of dynamic
critical behavior nor a power-law divergence of the magnetic correlation length
is found for the studied substitution range; this finding becomes increasingly
obvious with substitution. Finally, from SANS and magnetometry measurements, we
discern a crossover from easy-axis to easy-plane magneto-crystalline anisotropy
with increasing La substitution. These results indicate complex changes in
magnetic structure upon approaching the phase boundary.
