Magnetic properties and specific heat data of R11Ni4In9 (RÂ =Â Pr, Nd, Sm, Gd and Tb) compounds

Magnetic and thermal properties of R11Ni4In9 compounds (R = Pr, Nd, Sm, Gd and Tb) were investigated by means of magnetic and specific heat measurements. These compounds crystallize in orthorhombic Nd11Pd4In9-type crystal structure in which the rare earth atoms occupy five nonequivalent sublattices. For all these compounds except Gd11Ni4In9, the ground state at low temperature is antiferromagnetic. Except Pr11Ni4In9, in temperature dependence of the specific heat a two phase transitions are observed. For compounds with R = Nd and Tb with increasing of the external magnetic field and/or temperature the change to the ferrimagnetic state is observed. Sm11Ni4In9 is an antiferromagnet with small ferromagnetic component. The critical temperature of magnetic ordering does not fulfill the de Gennes scaling which indicates the influence of the crystal electric field in stabilizing the magnetic ordering.