title: Anisotropic electronic state via spontaneous phase separation in strained vanadium dioxide films.
abstract: We resolved the enigma of anisotropic electronic transport in strained vanadium dioxide (VO2) films by inquiring into the role that strain plays in the nanoscale phase separation in the vicinity of the insulator-to-metal transition. The root source of the anisotropy was visualized as the formation of a peculiar unidirectional stripe state which accompanies the phase transition. Furthermore, nanoscale infrared spectroscopy unveils distinct facets of electron-lattice interplay at three different stages of the phase transition. These stages include the initial formation of sparse nonpercolating metallic domains without noticeable involvement of the lattice followed by an electron-lattice coupled anisotropic stripe state close to percolation which ultimately evolves into a nearly isotropic rutile metallic phase. Our results provide a unique mesoscopic perspective for the tunable macroscopic phenomena in strained metal oxide films.
authors.affiliation: Department of Physics, The University of California at San Diego, La Jolla, California 92093, USA.
authors.forename: M K
authors.initials: MK
authors.lastname: Liu
authors.forename: M
authors.initials: M
authors.lastname: Wagner
authors.forename: E
authors.initials: E
authors.lastname: Abreu
authors.forename: S
authors.initials: S
authors.lastname: Kittiwatanakul
authors.forename: A
authors.initials: A
authors.lastname: McLeod
authors.forename: Z
authors.initials: Z
authors.lastname: Fei
authors.forename: M
authors.initials: M
authors.lastname: Goldflam
authors.forename: S
authors.initials: S
authors.lastname: Dai
authors.forename: M M
authors.initials: MM
authors.lastname: Fogler
authors.forename: J
authors.initials: J
authors.lastname: Lu
authors.forename: S A
authors.initials: SA
authors.lastname: Wolf
authors.forename: R D
authors.initials: RD
authors.lastname: Averitt
authors.forename: D N
authors.initials: DN
authors.lastname: Basov