Magnetic and electronic transport properties of the novel compounds U2Co6Al19 and Th2Co6Al19

Experimental results on AC susceptibility, DC magnetization, electrical resistivity and magnetoresistivity up to 8 T have been obtained for a well annealed polycrystalline sample of the novel ternary aluminide U2Co6Al19. As a reference, similar experiments on the Th counterpart were also done. The U-containing aluminide exhibits two phase transitions at 8 and 12.5 K, probably of ferromagnetic and antiferromagnetic type, respectively. Moreover, U2Co6Al19 is a Kondo system showing the coherence effect below about 40 K. On the other hand, the Th counterpart showed unexpectedly a spin fluctuation behaviour, which was inferred from the broad maximum seen in its χ(T) dependence near 600 K. However, the low temperature variation of ρ(T) leads rather to an AT5/2 power dependence instead of to the AT2 one characteristic for a spin fluctuation behaviour