title: Potential Fluctuations at Low Temperatures in Mesoscopic-Scale SmTiO3/SrTiO3/SmTiO3Quantum Well Structures.
abstract: Heterointerfaces of SrTiO3with other transition metal oxides make up an intriguing family of systems with a bounty of coexisting and competing physical orders. Some examples, such as LaAlO3/SrTiO3, support a high carrier density electron gas at the interface whose electronic properties are determined by a combination of lattice distortions, spin-orbit coupling, defects, and various regimes of magnetic and charge ordering. Here, we study electronic transport in mesoscale devices made with heterostructures of SrTiO3sandwiched between layers of SmTiO3, in which the transport properties can be tuned from a regime of Fermi-liquid like resistivity (ρ ∝ T2) to a non-Fermi liquid (ρ ∝ T5/3) by controlling the SrTiO3thickness. In mesoscale devices at low temperatures, we find unexpected voltage fluctuations that grow in magnitude as T 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.
authors.affiliation: Applied Physics Graduate Program, Smalley-Curl Institute, Rice University , Houston, Texas 77005, United States.
authors.forename: Will J
authors.initials: WJ
authors.lastname: Hardy
authors.affiliation: Materials Department, University of California, Santa Barbara , Santa Barbara, California 93106, United States.
authors.forename: Brandon
authors.initials: B
authors.lastname: Isaac
authors.affiliation: Materials Department, University of California, Santa Barbara , Santa Barbara, California 93106, United States.
authors.forename: Patrick
authors.initials: P
authors.lastname: Marshall
authors.affiliation: Materials Department, University of California, Santa Barbara , Santa Barbara, California 93106, United States.
authors.forename: Evgeny
authors.initials: E
authors.lastname: Mikheev
authors.affiliation: Department of Physics and Astronomy, Rice University , Houston, Texas 77005, United States.
authors.forename: Panpan
authors.initials: P
authors.lastname: Zhou
authors.affiliation: Materials Department, University of California, Santa Barbara , Santa Barbara, California 93106, United States.
authors.forename: Susanne
authors.initials: S
authors.lastname: Stemmer
authors.affiliation: Department of Physics and Astronomy, Rice University , Houston, Texas 77005, United States.|Department of Electrical and Computer Engineering, Rice University , Houston, Texas 77005, United States.|Department of Materials Science and Nanoengineering, Rice University , Houston, Texas 77005, United States.
authors.forename: Douglas
authors.identifier: 0000-0003-2370-9859
authors.initials: D
authors.lastname: Natelson
keywords: SmTiO3; SrTiO3; mesoscopic transport; oxide heterointerface; potential fluctuations; quantum well; rare earth titanate