abstract
The ferromagnetically coupled cobalt ion is observed to create a magnetocrystalline anisotropy in the PrNi5-xCox structure above a critical composition of x = 2. The competition of the anisotropy energies between Co and Pr sublattices gives rise to a spin reorientation (SR) phenomenon in PrNi5-xCox compounds at a low temperature (similar to 150 K) which is then followed by a magnetic transition at a higher temperature. Co-doping has a strong influence on the Curie temperature, changing it from similar to 60K (x = 1.95) to similar to 537K ( x = 3). The magnetic entropy change is associated with SR as well as a magnetic transition, and correspondingly a large full width at half maximum (delta T-FWHM) is obtained for this series of compounds. For example, the PrNi2.85Co2.15 compound presents delta T-FWHM = 166K at a 1 T field. This series therefore has an appreciable relative cooling power, which makes this material a suitable magnetic refrigerant over a large temperature span.
subject category
Physics
authors
Rocco, DL; Amaral, JS; Leitao, JV; Amaral, VS; Reis, MS; Das, S; Fernandes, RP; Araujo, JP; Pereira, AM; Tavares, PB; Martins, NV; Coelho, AA
our authors
João Cunha de Sequeira Amaral
Assistant Researcher
Vitor Brás Sequeira Amaral
Full professoracknowledgements
The authors thank FCT for the (i) VSM equipment (REEQ/1126/2001) and (ii) the project POCI/CTM/61284/2004. DLRocco thanks CICECO and FCT (SFRH/BPD/41927/2007) for the grant. Soma Das thanks FCT(SFRH/BPD/39262/2007) for the grant. J S Amaral acknowledges FCT for the grant (SFRH/BD/17961/2004).