  We have investigated the effect of temperature on magnetic properties of
Bi$_{0.9}$Gd$_{0.1}$Fe$_{1-x}$Ti$_x$O$_3$ (x = 0.00-0.20) multiferroic system.
Unexpectedly, the coercive fields ($H_{c}$) of this multiferroic system
increased with increasing temperature. The coercive fields and remanent
magnetization were higher over a wide range of temperatures in sample x = 0.10
i.e. in sample having composition Bi$_{0.9}$Gd$_{0.1}$Fe$_{0.9}$Ti$_{0.1}$O$_3$
than those of x = 0.00 and 0.20 compositions. Therefore, we have carried out
temperature dependent magnetization experiments extensively for sample x =
0.10. The magnetic hysteresis loops at different temperatures exhibit an
asymmetric shift towards the magnetic field axes which indicate the presence of
exchange bias effect in this material system. The hysteresis loops were also
carried out at temperatures 150 K and 250 K by cooling down the sample from 300
K in various cooling magnetic fields ($H_{cool}$). The exchange bias field
($H_{EB}$) values increased with $H_{cool}$ and decreased with temperature. The
$H_{EB}$ values were tunable by field cooling at temperatures up to 250 K.
