title: Longitudinal conductivity of LaF3/SrF2multilayer heterostructures.
abstract: LaF3/SrF2multilayer heterostructures with thicknesses of individual layers in the range 5-100 nm have been grown on MgO(100) substrates using molecular beam epitaxy. The longitudinal conductivity of the films has been measured using impedance spectroscopy in the frequency range 10-1-106Hz and a temperature range 300-570 K. The ionic DC conductivities have been determined from Nyquist impedance diagrams and activation energies from the Arrhenius-Frenkel equation. An increase of the DC conductivity has been observed to accompany decreased layer thickness for various thicknesses as small as 25 nm. The greatest conductivity has been shown for a multilayer heterostructure having thicknesses of 25 nm per layer. The structure has a conductivity two orders of magnitude greater than pure LaF3bulk material. The increasing conductivity can be understood as a redistribution of charge carriers through the interface due to differing chemical potentials of the materials, by strong lattice-constant mismatch, and/or by formation of a solid La1-xSrxF3-xsolution at the interface during the growth process.
authors.affiliation: Institute of Physics, Nanotechnology and Telecommunications, Peter the Great St. Petersburg Polytechnic University , Saint-Petersburg , Russia.
authors.forename: Tikhon
authors.initials: T
authors.lastname: Vergentev
authors.affiliation: Divisions of Solid State Physics and Physics of Dielectric and Semiconductors, Ioffe Institute , Saint-Petersburg , Russia.
authors.forename: Alexander
authors.initials: A
authors.lastname: Banshchikov
authors.affiliation: Institute of Physics, Nanotechnology and Telecommunications, Peter the Great St. Petersburg Polytechnic University , Saint-Petersburg , Russia.
authors.forename: Alexey
authors.initials: A
authors.lastname: Filimonov
authors.affiliation: Institute of Physics, Nanotechnology and Telecommunications, Peter the Great St. Petersburg Polytechnic University, Saint-Petersburg, Russia; Divisions of Solid State Physics and Physics of Dielectric and Semiconductors, Ioffe Institute, Saint-Petersburg, Russia.
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Koroleva
authors.affiliation: Divisions of Solid State Physics and Physics of Dielectric and Semiconductors, Ioffe Institute , Saint-Petersburg , Russia.
authors.forename: Nikolay
authors.initials: N
authors.lastname: Sokolov
authors.affiliation: Institute for Microproduction Technology, Leibniz University of Hanover , Garbsen , Germany.
authors.forename: Marc Christopher
authors.initials: MC
authors.lastname: Wurz
keywords: 103 Composites; 105 Low-Dimension (1D/2D) materials; 212 Surface and interfaces; 306 Thin film /Coatings; 40 Optical, magnetic and electronic device materials; Impedance spectroscopy; heterostructures; interfacial spacing; ionic conductivity; lanthanum fluoride; longitudinal conductivity; molecular beam epitaxy; strontium fluoride