Nuclear magnetic resonance studies of the non-Fermi-liquid alloys lanthanum uranium palladium aluminide

Since the discovery of strongly correlated electron systems that do not obey traditional Fermi-liquid (FL) theory in magnetic, transport and thermal properties, multiple attempts have been made to explain this note-Fermi-liquid (NFL) behavior. Nearness in the phase diagram to a quantum critical point, magnetic disorder and multiple channels through which conduction electrons can screen magnetic impurities are theoretical models that have been developed to explain this NFL behavior.; The electrical resistivity and specific heat properties of the alloy investigated in this dissertation, LaxU1-xPd 2Al3 (x = 0.8 and 0.9), have previously been determined to have NFL properties.; Nuclear magnetic resonance (NMR) measures the amount of magnetic disorder at the NMR nuclei site and thus can compare disorder driven NFL models to experiment. Initial NMR results on unaligned samples revealed an extremely broad, poorly resolved line shape. After magnetic alignment and subtraction of quadrupolar effects (quadrupolar frequency was found to be 0.98 MHz and the asymmetry parameter was found to be 0.27.), the effects of disorder induced magnetic broadening were observed. The amount, of magnetic disorder observed with NMR in LaxU1-xPd2Al3 agrees with disorder model prediction found by fitting disorder driven models (Kondo Disorder Model (KDM) and Griffiths McCoy phase model (GMPM)) to the magnetic susceptibility.; Fits of the KDM and GMPM to the magnetic susceptibility yield a distribution of energies that do not, extend down to zero Kelvin. It is in the limit in which there is a finite probability of obtaining characteristic energies at zero Kelvin that the uncompensated spins at finite temperatures give rise to NFL behavior. Thus it was determined that the distribution of energies is not significant enough to be the cause of NFL behavior as described by the KDM and GMPM.; In addition, fits of the GMPM to the magnetic susceptibility provide further evidence that disorder is not the driving mechanism behind the observed NFL behavior. In the GMPM fluctuations of rare clusters with large magnetic susceptibilities will give rise to singularities in the physical properties at low temperature. This is characterized by the fit parameter lambda which, if the value is less than one, will cause divergences in the specific heat and average magnetic susceptibility. The fit of the GMPM to the magnetic susceptibility produced lambda = 4.0 +/- 0.5 for La0.9U0.1Pd 2Al3. This value is large enough to make this model unable to describe the NFL behavior in this alloy.; In conclusion the KDM and the GMPM, while being able to describe the observed disorder in this alloy, cannot be considered the driving mechanism behind the NFL behavior. Theories based on proximity to a quantum critical point and multiple channels for screening magnetic impurities were not, ruled out by our investigation.