  Significative enhance in magnetocaloric effect due to finite size and surface
effects is reported in Terbium(Tb) thin films in the helimagnetic phase
(corresponding to a temperature range from $T_C$=219 K to $T_N$=231 K), for
external fields of the order of kOe. For a Tb thin film of 6 monolayers
submitted to an applied field ($\Delta$H= 30 kOe, $\Delta$H= 50 kOe and
$\Delta$H= 70 kOe) we report a significative change in adiabatic temperature,
$\Delta$T/$\Delta$H, near the N\'eel temperature, of the order ten times higher
than that observed for Tb bulk. On the other hand, for small values of the
magnetic field, large thickness effects are found. For external field strength
around few kOe, we have found that the thermal caloric efficiency increases
remarkably for ultrathin films. For an ultrathin film with 6 monolayers, we
have found $\Delta$T/$\Delta$H=43 K/T while for thicker films, with 20
monolayers, $\Delta$T/$\Delta$H=22 K/T. Our results suggest that thin films of
Tb are a promising material for magnetocaloric effect devices for applications
at intermediate temperatures.
