Cascade of magnetic transitions in the frustrated antiferromagnetic CePtPb

CePtPb is an antiferromagnetic, heavy-fermion, metallic compound that crystallizes in the ZrNiAl-type structure with space group P-62m, where the Ce-ions form a quasi-Kagome lattice in the ab-plane. Other compounds in this family with a quasi-Kagome magnetic lattice such as CePdAl and YbAgGe have shown a complex temperature-versus-magnetic field (T-H) phase diagram with multiple magnetically-ordered phases. In this thesis, a T-H phase diagram for single crystal CePtPb is constructed from electric resistivity and specific heat measurements. The constructed phase diagram also shows multiple magnetically-ordered phases as the Neel temperature T_N=0.9 K is suppressed continuously to T=0.4 K by applied field with an extrapolated zero-temperature critical field H_c=7 kOe. In zero-field, muon spin relaxation measurements show residual spin dynamics at 25 mK, consistent with the magnetic structure proposed for CePdAl, where 2/3 of the Ce-4f spins order antiferromagnetically and the other 1/3 of the Ce-4f spins remain fluctuating. From a power-law analysis of the electrical resistivity p=p_0+AT^n), neither Fermi-liquid (n=2) nor non-Fermi-liquid (n=H_c. Instead, there is an anomalous evolution of n that increases from n=2.5 at H=H_c to n=4.1 at H=90 kOe, with a tendency towards saturation near the value n~4 for H>30 kOe. The phase diagram and the measurements are compared to CePdAl and YbAgGe.