Quasi-Two-Dimensional Mott Transition SystemCa2−xSrxRuO4

Abstract

We have revealed the phase diagram of ${\mathrm{Ca}}_{2-x}{\mathrm{Sr}}_x{\mathrm{RuO}}_4$: the quasi-two-dimensional Mott transition system that connects the Mott insulator ${\mathrm{Ca}}_2{\mathrm{RuO}}_4$ with the spin-triplet superconductor ${\mathrm{Sr}}_2{\mathrm{RuO}}_4$. Adjacent to the metal/nonmetal transition at $x\simeq 0.2$, we found an antiferromagnetically correlated metallic region where non-Fermi-liquid behavior in resistivity is observed. Besides this, the critical enhancement of susceptibility toward the region boundary at $x_{\mathrm{c}}\simeq 0.5$ suggests the crossover of magnetic correlation to a nearly ferromagnetic state, which evolves into the spin-triplet superconductor ${\mathrm{Sr}}_2{\mathrm{RuO}}_4$.