title: A metal-insulator transition in R2O2Bi with an unusual Bi2- square net (R = rare earth or Y).
abstract: A series of tetragonal ThCr(2)Si(2)-type compounds, R(2)O(2)Bi (R = rare earth or Y), are synthesized in which an unusual Bi(2-) anion forms a square net layer that is sandwiched between (R(2)O(2))(2+) fluorite layers. Two-dimensional (2D) electronic bands around the Fermi energy are predominantly composed of 6p(x)6p(y) orbitals in the Bi(2-) square net, which contains a positive hole per Bi(2-) ion. The decrease in the size of the square net caused by reducing the size of the R ion enhances the electrical conductivity because of the hole, resulting in a "chemical pressure"-induced metal-insulator transition.
authors.affiliation: Frontier Research Center, Tokyo Institute of Technology, Midori-ku, Yokohama, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Mizoguchi
authors.forename: Hideo
authors.initials: H
authors.lastname: Hosono