Magnetic phase transition and magnetocaloric effect in PrCo9Si4 and NdCo9Si4

The compounds, PrCo9Si4 and NdCo9Si4, have been recently reported to exhibit first-order ferromagnetic transitions near 24 K. We have subjected this compound for further characterization by magnetization, heat-capacity and electrical resistivity (p) measurements at low temperatures in the presence of magnetic fields, particularly to probe magnetocaloric effect and magnetoresistance. The compounds are found to exhibit rather modest magnetocaloric effect at low temperatures peaking at Curie temperature, tracking the behaviour of magnetoresistance. The magnetic transition does not appear to be first order in the present investigations. (C) 2007 Elsevier Ltd. All rights reserved.