  We report the effect of exchange frustration on the magnetocaloric properties
of GdCrTiO$_5$ compound. Due to the highly exchange-frustrated nature of
magnetic interaction, in GdCrTiO$_5$, the long-range antiferromagnetic ordering
occurs at much lower temperature $T_N$=0.9 K and the magnetic cooling power
enhances dramatically relative to that observed in several geometrically
frustrated systems. Below 5 K, isothermal magnetic entropy change (-$\Delta
S_{\rm m}$) is found to be 36 J kg$^{-1}$ K$^{-1}$, for a field change ($\Delta
H$) of 7 T. Further, -$\Delta S_{\rm m}$ does not decrease from its maximum
value with decreasing in $T$ down to very low temperatures and is reversible in
nature. The adiabatic temperature change, $\Delta T_{\rm ad}$, is 15 K for
$\Delta H$=7 T. These magnetocaloric parameters are significantly larger than
that reported for several potential magnetic refrigerants, even for small and
moderate field changes. The present study not only suggests that GdCrTiO$_5$
could be considered as a potential magnetic refrigerant at cryogenic
temperatures but also promotes further studies on the role of exchange
frustration on magnetocaloric effect. In contrast, only the role of geometrical
frustration on magnetocaloric effect has been previously reported theoretically
and experimentally investigated on very few systems.
