Specific heat studies of RCu 2Si 2 (R=Tb, Ho) and RCu 2Ge 2 (R=Gd, Tb) compounds

Abstract

Magnetic properties of RCu 2Si 2 (R=Tb, Ho) and RCu 2Ge 2 (R=Gd, Tb), crystallizing with the tetragonal ThCr 2Si 2-type crystal structure, were investigated by means of magnetic and calorimetric measurements. All compounds exhibit antiferromagnetic ordering below T N equal to 11.2 K for TbCu 2Si 2, 5.3 K for HoCu 2Si 2, 12.0 K for GdCu 2Ge 2 and 12.5 K for TbCu 2Ge 2. At temperatures of T t = 8.5 K for TbCu 2Si 2 and 9.8 K for TbCu 2Ge 2 additional phase transitions were observed. Apart from the investigation on magnetic phase transitions, magnetic contributions to the specific heat were analyzed in terms of Schottky effect. The corresponding crystal electric field (CEF) level splitting schemes were calculated. Moreover, the phononic characteristic temperatures were estimated.