  Muon spin relaxation ($\mu$SR) measurements in high transverse magnetic
fields ($\parallel \hat c$) revealed strong field-induced quasi-static
magnetism in the underdoped and Eu doped (La,Sr)$_{2}$CuO$_{4}$ and
La$_{1.875}$Ba$_{0.125}$CuO$_{4}$, existing well above $T_{c}$ and $T_{N}$. The
susceptibility-counterpart of Cu spin polarization, derived from the muon spin
relaxation rate, exhibits a divergent behavior towards $T \sim 25$ K. No
field-induced magnetism was detected in overdoped
La$_{1.81}$Sr$_{0.19}$CuO$_{4}$, optimally doped Bi2212, and Zn-doped
YBa$_{2}$Cu$_{3}$O$_{7}$.
