Strongly correlated electron behaviour in CeT₂Al₈ (T = Fe, Co)

We report on studies of physical properties of the two compounds CeFe ₂Al₈ and CeCo₂Al₈ in which we have found varying degrees of electronic correlational phenomena. No magnetic ordering was detected down to 0.4 K in either of the two compounds. At elevated temperatures an incoherent Kondo interaction between the Ce 4f-electron and the conduction electrons is prevalent in both compounds. CeCo₂Al ₈ exhibits a stable 4f-electron magnetic moment, but in CeFe2Al8 an intermediate-valent state prevails near room temperature that eventually transforms into a Fermi-liquid ground state. The low-temperature specific heat of CeCo₂Al₈ shows typical strongly correlated electron behaviour and a - log T upturn in its electronic specific heat below about 10 K.