Magnetic and related properties of U4Rh13Si9 and U4Ir13Si9

The compounds U4Rh13Si9 and U4Ir13Si9 crystallize with the orthorhombic Er4Ir13Si9-type structure that contains three non-equivalent positions of uranium atoms. Their magnetic, electrical transport and thermal properties were studied down to liquid helium temperature in magnetic fields up to 9 T. Both compounds have been found to order antiferromagnetically at low temperatures and to exhibit complex magnetic behavior in the ordered state. Some features characteristic of spin fluctuators (U4Rh13Si9) and Kondo lattices (U4Ir13Si9) indicate that the two ternaries studied are novel strongly correlated electron systems.