title: A surface-tailored, purely electronic, mott metal-to-insulator transition.
abstract: Mott transitions, which are metal-insulator transitions (MITs) driven by electron-electron interactions, are usually accompanied in bulk by structural phase transitions. In the layered perovskite Ca(1.9)Sr(0.1)RuO4, such a first-order Mott MIT occurs in the bulk at a temperature of 154 kelvin on cooling. In contrast, at the surface, an unusual inherent Mott MIT is observed at 130 kelvin, also on cooling but without a simultaneous lattice distortion. The broken translational symmetry at the surface causes a compressional stress that results in a 150% increase in the buckling of the Ca/Sr-O surface plane as compared to the bulk. The Ca/Sr ions are pulled toward the bulk, which stabilizes a phase more amenable to a Mott insulator ground state than does the bulk structure and also energetically prohibits the structural transition that accompanies the bulk MIT.
authors.affiliation: Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: R G
authors.initials: RG
authors.lastname: Moore
authors.forename: Jiandi
authors.initials: J
authors.lastname: Zhang
authors.forename: V B
authors.initials: VB
authors.lastname: Nascimento
authors.forename: R
authors.initials: R
authors.lastname: Jin
authors.forename: Jiandong
authors.initials: J
authors.lastname: Guo
authors.forename: G T
authors.initials: GT
authors.lastname: Wang
authors.forename: Z
authors.initials: Z
authors.lastname: Fang
authors.forename: D
authors.initials: D
authors.lastname: Mandrus
authors.forename: E W
authors.initials: EW
authors.lastname: Plummer