Lattice specific heat for the RMIn5 (R=Gd, La, Y; M=Co, Rh) compounds: Non-magnetic contribution subtraction

J.I. FACIO; D. BETANCOURTH; N.R. CEJAS BOLECEK; G.A. JORGE; P. PEDRAZZINI; V.F. CORREA; PABLO S. CORNAGLIA; VERONICA LAURA VILDOSOLA; D.J. GARCÍA

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016 vol. 407 p. 406 - 411

0304-8853

We analyze theoretically a common experimental process used to obtain the magnetic contribution tothe specific heat of a given magnetic material. In the procedure, the specific heat of a non-magneticanalog is measured and used to subtract the non-magnetic contributions, which are generally dominatedby the lattice degrees of freedom in a wide range of temperatures.We calculate the lattice contribution to the specific heat for the magnetic compounds GdMIn 5(M 1⁄4Co, Rh) and for the non-magnetic YMIn 5 and LaMIn 5 (M 1⁄4Co, Rh), using density functional theorybased methods. We find that the best non-magnetic analog for the subtraction depends on the magneticmaterial and on the range of temperatures. While the phonon specific heat contribution of YRhIn 5 is anexcellent approximation to the one of GdCoIn 5 in the full temperature range, for GdRhIn 5 we find a betteragreement with LaCoIn 5 , in both cases, as a result of an optimum compensation effect between massesand volumes. We present measurements of the specific heat of the compounds GdMIn 5 (M 1⁄4Co, Rh) upto room temperature where it surpasses the value expected from the Dulong?Petit law. We obtain a goodagreement between theory and experiment when we include anharmonic effects in the calculations.