  Oxide interfaces, including the LaAlO3/SrTiO3 interface, have been a subject
of intense interest for over a decade due to their rich physics and potential
as low dimensional nanoelectronic systems. The field has reached the stage
where efforts are invested in developing devices. It is critical now to
understand the functionalities and limitations of such devices. Recent scanning
probe measurements of the LaAlO3/SrTiO3 interface have revealed locally
enhanced current flow and accumulation of charge along channels related to
SrTiO3 structural domains. These observations raised a key question regarding
the role these modulations play in the macroscopic properties of devices. Here
we show that the microscopic picture, mapped by scanning superconducting
quantum interference device, accounts for a substantial part of the
macroscopically measured transport anisotropy. We compared local flux data with
transport values, measured simultaneously, over various SrTiO3 domain
configurations. We show a clear relation between maps of local current density
over specific domain configurations and the measured anisotropy for the same
device. The domains divert the direction of current flow, resulting in a
direction dependent resistance. We also show that the modulation can be
significant and that in some cases up to 95% of the current is modulated over
the channels. The orientation and distribution of the SrTiO3 structural domains
change between different cooldowns of the same device or when electric fields
are applied, affecting the device behavior. Our results, highlight the
importance of substrate physics, and in particular, the role of structural
domains, in controlling electronic properties of LaAlO3/SrTiO3 devices.
Further, these results point to new research directions, exploiting the STO
domains ability to divert or even carry current.
