Graphene probe to explore the surface polarization in SrTiO3 without damage

Graphene is utilized as a sensitive probe to explore the surface polarization phenomenon in SrTiO3 in this work. A ferroelectric-like hysteresis effect induced by the external electric field stimuli as well as a pyroelectric effect caused by the light stimuli is observed and discussed through the quasi-static/transient evolution of graphene current at a constant bias voltage. The existence of electric dipoles at the surface of SrTiO3 is confirmed. Dipoles are dependent on the external electric field, and there is an electric field induced remanent polarization after high electric field treatment. The pyroelectric phenomenon caused by the light illumination indicates that the electric dipoles naturally exist at the SrTiO3 surface even though there is no external electric field.