Strongly Correlated Electron Behavior in R2Os3Al9 (R =U, Ce)

We report two new orthorhombic compounds U₂Os₃Al₉ and Ce₂Os₃Al₉ showing signatures of strongly correlated electron behavior. The U-compound orders antiferromagnetically at 7 K inferred from magnetization and heat capacity. The resistivity data reveal a heavy fermion, Kondo like behavior with a negative temperature coefficient below 300 K. However, Ce₂Os₃Al₉ shows Pauli paramagnetic behavior with a magnitude of susceptibility and the electronic heat capacity similar to that of intermediate valent systems.