1 research outputs found
Potential Fluctuations at Low Temperatures in Mesoscopic-Scale SmTiO<sub>3</sub>/SrTiO<sub>3</sub>/SmTiO<sub>3</sub> Quantum Well Structures
Heterointerfaces
of SrTiO<sub>3</sub> with other transition metal
oxides make up an intriguing family of systems with a bounty of coexisting
and competing physical orders. Some examples, such as LaAlO<sub>3</sub>/SrTiO<sub>3</sub>, support a high carrier density electron gas at
the interface whose electronic properties are determined by a combination
of lattice distortions, spināorbit coupling, defects, and various
regimes of magnetic and charge ordering. Here, we study electronic
transport in mesoscale devices made with heterostructures of SrTiO<sub>3</sub> sandwiched between layers of SmTiO<sub>3</sub>, in which
the transport properties can be tuned from a regime of Fermi-liquid
like resistivity (Ļ ā <i>T</i><sup>2</sup>)
to a non-Fermi liquid (Ļ ā <i>T</i><sup>5/3</sup>) by controlling the SrTiO<sub>3</sub> thickness. In mesoscale devices
at low temperatures, we find unexpected voltage fluctuations that
grow in magnitude as <i>T</i> is decreased below 20 K, are
suppressed with increasing contact electrode size, and are independent
of the drive current and contact spacing distance. Magnetoresistance
fluctuations are also observed, which are reminiscent of universal
conductance fluctuations but not entirely consistent with their conventional
properties. Candidate explanations are considered, and a mechanism
is suggested based on mesoscopic temporal fluctuations of the Seebeck
coefficient. An improved understanding of charge transport in these
model systems, especially their quantum coherent properties, may lead
to insights into the nature of transport in strongly correlated materials
that deviate from Fermi liquid theory