Seminars Archive
Electronic structure of quasi-one-dimensional monophosphate tungsten bronzes.
Abstract
Friday, September 12, 2003, 15:00
Seminar Room, ground floor, Building "T"
Sincrotrone Trieste, Basovizza
Electronic structure of quasi-one-dimensional monophosphate
tungsten bronzes.
Lydia Roca
( Instituto de Ciencias de Materiales de Madrid, CSIC. Cantoblanco
28049 Madrid and
LURE, Centre Universitaire Paris-Sud,Orsay cedex, France)
Abstract
The monophosphate tungsten bronzes exhibit quasi-low-dimensional structural
and electronic-transport properties similar to those observed in the molybdenum
bronzes [1,2]. Their structure is characterized by ReO3-type slabs
of WO6 octahedra connected by PO4 tetrahedra. Several theoretical calculations
show that the electronic structure has 1D and 2D-like bands. It is suggested
that the existence of a charge density wave [3] is due to the 1D nested
Fermi surface [4].
Synchrotron-radiation excited Angle Resolved Photoemission measurements
of the Kx(PO2)4(WO3)8 compounds are reported. The experiments were done
at the SU8 beamline at LURE. This experimental system is designed to measure
in two different detection geometries: even and odd. This allows
to distinguish the symmetry of the detected states.
The electronic band structure was measured along the GX and GY high
symmetry directions in different Kx(PO2)4(WO3)8 compounds. The 1D and 2D
conduction contributions have been identified. Different behaviors as a
function of the doping level, x, have been found. The experimental Fermi
surface (FS) was also obtained. The analysis reveals the existence of some
parallel portions, associated to the nesting mechanism.
[1] Physics and Chemistry of low dimensional inorganic conductors, Ed.
C. Schlenker, M. Greenblatt, J. Dumas, S. van Smaalen (Plenum, NATO ASI
series, 1996)
[2] Z. S, Teweldemedhin et al, Phys. Rev. B 46, 7897 (1992)
[3] P. Foury et al, Int. J. Mod. Phys. B 7, 4005 (1993)
[4] P. Roussel et al, Eur. Phys. J. B 12, 497 (1999)
[5] E. Canadell et al, Inorg. Chem. 29, 3871 (1990)
[6] E. Canadell et al, Phys. Rev. B 43, 1894 (1991)
