  Charge transport through metal-Mott-insulator interfaces is studied and
compared with that through metal-band-insulator interfaces. For band
insulators, rectification has been known to occur owing to a Schottky barrier,
which is produced by the work-function difference. For Mott insulators,
however, qualitatively different current-voltage characteristics are obtained.
Theoretically, we use the one-dimensional Hubbard model for a Mott insulator
and attach to it the tight-binding model for metallic electrodes. A Schottky
barrier is introduced by a solution to the Poisson equation with a simplified
density-potential relation. The current density is calculated by solving the
time-dependent Schr\"odinger equation. We mainly use the time-dependent
Hartree-Fock approximation, and also use exact many-electron wave functions on
small systems for comparison. Rectification is found to be strongly suppressed
even for large work-function differences. We show its close relationship with
the fact that field-effect injections into one-dimensional Mott insulators are
ambipolar. Experimentally, we fabricated asymmetric contacts on top of single
crystals of quasi-one-dimensional organic Mott and band insulators.
Rectification is strongly suppressed at an interface between metallic magnesium
and Mott-insulating (BEDT-TTF)(F$_2$TCNQ)
[BEDT-TTF=bis(ethylenedithio)tetrathiafulvalene,
F$_2$TCNQ=2,5-difluorotetracyanoquinodimethane].
