Heavy-Mass Fermi Liquid near a Ferromagnetic Instability in Layered Ruthenates

Low temperature magnetic, thermal, and transport measurements in ${\mathrm{C}\mathrm{a}}_{2-x}{\mathrm{S}\mathrm{r}}_x{\mathrm{R}\mathrm{u}\mathrm{O}}_4$ clarify the appearance of a cluster glass phase, after the evolution of a nearly ferromagnetic heavy-mass Fermi liquid from the spin-triplet superconductor ${\mathrm{S}\mathrm{r}}_2{\mathrm{R}\mathrm{u}\mathrm{O}}_4$. As the Mott transition is approached across a 2nd-order structural transition, both the magnetization and specific heat decrease considerably while the transport scattering rate diverges. A metamagnetic transition to a highly spin polarized state, with a local moment $S=1/2$, is observed. We argue that an orbital rearrangement with Ca substitution changes itinerant ferromagnetism to antiferromagnetism of localized moments.