Band-width control in a perovskite-type 3d^1 correlated metal Ca_{1-x}Sr_xVO_3. I. Evolution of the electronic properties and effective mass

Abstract

Single crystals of the perovskite-type $3d^1$ metallic alloy system Ca${}_{1-x}$Sr${}_x$VO${}_3$ were synthesized in order to investigate metallic properties near the Mott transition. The substitution of a Ca${}^{2+}$ ion for a Sr${}^{2+}$ ion reduces the band width $W$ due to a buckling of the V-O-V bond angle from $\sim 180^{\circ }$ for SrVO${}_3$ to $\sim 160^{\circ }$ for CaVO${}_3$. Thus, the value of $W$ can be systematically controlled without changing the number of electrons making Ca${}_{1-x}$Sr${}_x$VO${}_3$: one of the most ideal systems for studying band-width effects. The Sommerfeld-Wilson's ratio ($\simeq 2$), the Kadowaki-Woods ratio (in the same region as heavy Fermion systems), and a large $T^2$ term in the electric resistivity, even at 300 K, substantiate a large electron correlation in this system, though the effective mass, obtained by thermodynamic and magnetic measurements, shows only a systematic but moderate increase in going from SrVO${}_3$ to CaVO${}_3$, in contrast to the critical enhancement expected from the Brinkmann-Rice picture. It is proposed that the metallic properties observed in this system near the Mott transition can be explained by considering the effect of a non-local electron correlation.

14 pages in a Phys. Rev. B camera-ready format with 10 EPS figures embedded. LaTeX 2.09 source file using "camera.sty" and "prbplug.sty" provided by N. Shirakawa. For OzTeX (Macintosh), use "ozfig.sty" instead of "psfig.sty". "ozfig.sty" can be also obtained by e-mail request to N. Shirakawa: <[email protected]>. Submitted to Phys. Rev. B