Effect of Tb/Gd substitution on crystal structure and exchange interactions of Gd1- xTb xNi 3 intermetallic compounds

Abstract

In the paper an in uence of Tb/Gd substitution on crystal structure and exchange interactions of Gd1􀀀xTbxNi3 (x = 0:0, 0.5, 0.8, 1.0) polycrystalline compounds have been studied. The crystal structure of all samples was checked at the room temperature by means of X-ray di raction. Exchange integrals of R R (JRR), T T (JTT) and R T (JRT) atoms were evaluated from M(T) magnetization curves (2 300 K, 2 T) based on the mean eld theory calculation. As it was shown the samples examined are single phase and crystallize in the PuNi3 (space group R-3m) type of crystal structure. The Tb/Gd substitution causes the decrease of lattice parameters as well as the volume of the unit cell. With increase of the x parameter the magnetic moment of Tb atoms increases from 6.94 B (x = 0:5) to 8.12 B (x = 1). The M(T) dependence of the examined compounds depends almost 8 times stronger on exchange interactions within the R R site than the interactions between the two antiferromagnetically coupled magnetic sublattices R T.