  The electron band structure of graphene on SrTiO3 substrate has been
investigated as a function of temperature. The high-resolution angle-resolved
photoemission study reveals that the spectral width at Fermi energy and the
Fermi velocity of graphene on SrTiO3 are comparable to those of graphene on a
BN substrate. Near the charge neutrality, the energy-momentum dispersion of
graphene exhibits a strong deviation from the well-known linearity, which is
magnified as temperature decreases. Such modification resembles the
characteristics of enhanced electron-electron interaction. Our results not only
suggest that SrTiO3 can be a plausible candidate as a substrate material for
applications in graphene-based electronics, but also provide a possible route
towards the realization of a new type of strongly correlated electron phases in
the prototypical two-dimensional system via the manipulation of temperature and
a proper choice of dielectric substrates.
