  The effect of external pressure on the magnetic properties and magnetocaloric
effect of R(Co1-xSix)2 [R= Er, Dy and x=0, 0.025 and 0.05] compounds has been
studied. The ordering temperatures of both the parent as well as the Si
substituted compounds are found to decrease with pressure. In all the
compounds, the critical field for metamagnetic transition increases with
pressure. It is seen that the magnetocaloric effect in the parent compounds is
almost insensitive to pressure, while there is considerable enhancement in the
case of Si substituted compounds. Spin fluctuations arising due to the
magnetovolume effect play a crucial role in determining the pressure dependence
of magnetocaloric effect in these compounds. Analysis of the magnetization data
using the Landau theory has shown that the magnitude of the Landau coefficient
(C3) decreases with Si concentration whereas it is found to increase with
pressure. The isothermal magnetic entropy change is found to behave in the same
manner as C3, both with Si concentration (at ambient pressure) as well as with
the applied pressure.
