R. Pietri

Effect of Th-substitution in a new dense-Kondo compound UCu5Al

Abstract We have investigated magnetic, electrical, and thermodynamic properties of a new system U1−xThxCu5Al. We have found that these alloys are antiferromagnetically ordered Kondo systems and exhibit moderate heavy fermion behaviour at low temperatures.

μSR in Ce1-xLaxAl3: anisotropic Kondo effect?

Zero-field μ + spin relaxation experiments in the heavy-fermion alloys Ce 1-x La x Al 3 , x = 0 and 0.2, examine a recent proposal that the system exhibits a strong anisotropic Kondo effect. We resolve a damped oscillatory component for both La concentrations, indicative of disordered antiferromagnetism. For x = 0.2 the oscillation frequency decreases smoothly with increasing temperature, and vanishes at the specific heat anomaly temperature T*2.2 K. Our results are consistent with the view that T* is due to a magnetic transition rather than anisotropic Kondo behavior.

Magnetic frustrations and magnetic order in CeAl3 and related alloys

Abstract Pseudobinary Ce 1− x La x Al 3 and Ce 1− x Y x Al 3 alloys have been studied via X-ray diffraction, magnetic susceptibility and specific heat. The heavy fermion state in CeAl 3 is unstable toward local-moment antiferromagnetism. Our results imply the heavy fermion state and magnetic order are mutually exclusive in this compound.

The alloying study of CeAl3

Abstract We have studied low temperature properties of CeAl3 as a function of both negative (La) and positive (Y) chemical lattice pressure. The changes of the lattice constants due to positive chemical pressure are strongly anisotropic and similar to those caused by the application of hydrostatic pressure. We have shown that the evolution of the low temperature anomaly cannot be explained by the changes of lattice constants nor by atomic disorder alone. We have suggested a new non-Fermi liquid tuning mechanism.

Magnetic field study of Ce0.8La0.2Al3

A partial substitution of La for Ce in CeAl3 leads to large anomalies in the low temperature specific heat, presumably of magnetic origin, and results in a strong reduction of γ. Magnetic fields up to 14 T have little effect on the temperature position of the anomaly in Ce0.8La0.2Al3 but attenuate its magnitude. Specific heats of Ce0.8La0.2Al3 and CeAl3 approach each other in large fields of order 14 T. Magnetic fields increase γ of Ce0.8La0.2Al3.