  A comprehensive study of impurity-induced magnetism in nonmagnetically
(Mg${}^{2+}$) and magnetically (Co${}^{2+}$) doped
PbNi${}_{2}$V${}_{2}$O${}_{8}$ compounds is given, using both macroscopic dc
susceptibility and local-probe electron spin resonance (ESR) techniques.
Magnetic coupling between impurity-liberated spins is estimated from a
linewidth of low-temperature ESR signal in Mg-doped samples. In addition, in
the case of magnetic cobalt dopants the impurity-host magnetic exchange is
evaluated from the Co-induced contribution to the linewidth in the paramagnetic
phase. The experimentally observed severe broadening of the ESR lines in the
magnetically doped compounds with respect to nonmagnetic doping is attributed
to a rapid spin-lattice relaxation of the Co${}^{2+}$ ions, which results in a
bottleneck-type of temperature dependence of the induced linewidth. The
exchange parameters obtained from the ESR analysis offer a satisfactory
explanation of the observed low-temperature magnetization in doped samples.
