Neutron scattering studies of an antiferromagnetic Kondo compound: Ce8Pd24Ga

The antiferromagnet Ce8Pd24Ga with T-N = 3.1 K has been investigated using neutron diffraction, inelastic neutron scattering, electrical resistivity, magnetoresistance and magnetic susceptibility measurements. Rietveld analys is of neutron diffraction data reveals that Ce8Pd24Ga crystallizes in the c ubic structure with space group Pm (3) over barm. Inelastic neutron scatter ing (INS) studies show two well-defined crystal-field excitations at 3.2 me V and 12.8 meV. The crystal-field parameters have been estimated from the a nalysis of INS data. The heat capacity calculated from the crystal-field le vel scheme shows a Schottky peak at 15 K which agrees well with the reporte d experimental results. The resistivity exhibits - In T behaviour at high t emperature followed by a peak at 8 K and eventually drops at T-N The peak i n the resistivity at 8 K arises due to the combined effect of crystalline e lectric fields and Kondo interactions. The analysis of the resistivity data in the magnetically ordered state reveals a gap of 16.1 K in the spin-wave spectrum. At 1.8 K the magnetoresistance is positive and it changes to neg ative at 3 K. The positive magnetoresistance at 1.8 K is consistent with th e antiferromagnetic ground state. The negative magnetoresistance shows a sc aling behaviour that yields a low-temperature Kondo temperature of 5.8 K. T he magnetic susceptibility exhibits Curie-Weiss behaviour between 20 K and 300 K with an effective paramagnetic moment mu (eff) = 2.33 mu (B) and para magnetic Curie temperature theta (p) = -18.8 K. The present studies reveal that the physical properties of Ce8Pd24Ga are governed by the Kondo, crysta l-field and Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions.