  The three primary ferroics, namely ferromagnets, ferroelectrics and
ferroelastics exhibit corresponding large (or even giant)
magnetocaloric,electrocaloric and elastocaloric effects when a phase transition
is induced by the application of an appropriate external field. Recently the
suite of primary ferroics has been extended to include ferrotoroidic materials
in which there is an ordering of toroidic moments in the form of magnetic
vortex-like structures, examples being LiCo(PO_4)_3 and Ba_2CoGe_2O_7. In the
present work we formulate the thermodynamics of ferrotoroidic materials. Within
a Landau free energy framework we calculate the toroidocaloric effect by
quantifying isothermal entropy change (or adiabatic temperature change) in the
presence of an applied toroidic field when usual magnetization and polarization
may also be present simultaneously. We also obtain a nonlinear
Clausius-Clapeyron relation for phase coexistence.
