The magnetic susceptibility and nuclear magnetic resonance (NMR) linewidth have been measured in the heavy-fermion alloys CePtSi1-xGe x, x=0 and 0.1, to study the role of disorder in the non-Fermi-liquid (NFL) behavior of this system. The theoretical NMR line shape is calculated from disorder-driven NFL models and shows the same essential features as the observed spectra. Analysis of 29Si and 195Pt NMR linewidths strongly suggests the existence of locally inhomogeneous susceptibility in both materials, and agrees with the widths of the local susceptibility distributions estimated from the susceptibility fits to the disorder-driven NFL models. Disorder-driven mechanisms can also explain the NFL behavior in CePtSi0.9Ge0.1; the NMR spectra do not, however, distinguish between the Kondo-disorder and Griffiths phase models. We find that stoichiometric CePtSi and Ge-doped CePtSi0.9Ge 0.1 show similar degrees of magnetic disorder, although a narrower distribution of local susceptibilities in CePtSi allows Fermi-liquid behavior to appear below 1 K. The residual resistivity reported in CePtSi is relatively large, which indicates a significant level of intrinsic lattice defects and seems to be consistent with the disorder observed in the NMR spectra.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - 1 Jul 2004|