  Bianchi type $VI_{0}$ massive string cosmological models using the technique
given by Letelier (1983) with magnetic field are investigated. To get the
deterministic models, we assume that the expansion ($\theta$) in the model is
proportional to the shear ($\sigma$) and also the fluid obeys the barotropic
equation of state. It was found that vacuum energy density $\Lambda \propto
\frac{1}{t^{2}}$ which matches with natural units. The behaviour of the models
from physical and geometrical aspects in presence and absence of magnetic field
is also discussed.
