Seoul Natl Univ Dept Phys Seoul 151742 South Korea
Max Planck Inst Festkorperforsch D-70569 Stuttgart Germany
Chonnam Natl Univ Dept Phys Kwangju 500757 South Korea
Pusan Natl Univ Rcdamp Pusan 609735 South Korea
Pusan Natl Univ Dept Phys Pusan 609735 South Korea
Los Alamos Natl Lab Supercond Technol Ctr Los Alamos Nm 87545

We investigated optical properties of (Ca,Sr)RuO3 films on the borderline of a metal-insulator transition. Our results show all of the predicted characteristics for a metallic Mott-Hubbard system, including (i) a mass enhancement in de limit, (ii) a U/2 excitation, and (iii) a U excitation. Also, self-consistency is exploited within the Gutzwiller-Brinkman-Rice picture for the Mott transition. Our finding displays that electron correlation should be important even in 4d materials. However, low frequency behaviors of electrodynamic quantities suggest extra scattering mechanisms in addition to the Mott-Hubbard correlation.
 

Physical Review Letters, 82 5321-5324, 1999.