μSR in Ce1-xLaxAl3: anisotropic Kondo effect?

Zero-field μ+ spin relaxation experiments in the heavy-fermion alloys Ce1-xLaxAl3, 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