Contribution of paramagnetic entropy to magnetocaloric effect in La(FexSi1-x)13.

To evaluate paramagnetic fluctuations and their contribution to entropy change of magnetic phase transition, paramagnetic susceptibility of La(Fe0.88Si0.12) was investigated after modifying the magnetic state by application of pressure or by the partial substitution of Ce or Al. Volume reduction by hydrostatic pressure or partial substitution of Ce maintains the value of effective moment peff, and comparison of peff with spontaneous moment at ground state suggests the appearance of disordered local moment in the paramagnetic phase. Reduction of the paramagnetic Curie temperature θp by these modifications is faster than that of the Curie temperature TC. Change in the difference TC -θP is equivalent to that in the entropy change ΔSCC obtained from the Clausius-Clapeyron relation. On the contrary, partial substitution of Al brings about an increase of itinerant character, accompanying a reduction of ΔSCC. [ABSTRACT FROM AUTHOR]