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Orbital control of effective dimensionality: from spin-orbital fractionalization to confinement in the anisotropic ladder system CaCu(2)O(3).

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Publication date 2015
Author Bisogni Valentina, Wohlfeld Krzysztof, Nishimoto Satoshi, Monney Claude, Trinckauf Jan, Zhou Kejin, Kraus Roberto, Koepernik Klaus, Sekar Chinnathambi, Strocov Vladimir, Büchner Bernd, Schmitt Thorsten, van den Brink Jeroen, Geck Jochen,
Project Mott Physics Beyond the Heisenberg Model in Iridates and Related Materials
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Original article (peer-reviewed)

Journal Physical review letters
Volume (Issue) 114(9)
Page(s) 096402 - 096402
Title of proceedings Physical review letters
DOI 10.1103/PhysRevLett.114.096402

Abstract

Fractionalization of an electronic quasiparticle into spin, charge, and orbital parts is a fundamental and characteristic property of interacting electrons in one dimension. However, real materials are never strictly one dimensional and the fractionalization phenomena are hard to observe. Here we studied the spin and orbital excitations of the anisotropic ladder material CaCu_{2}O_{3}, whose electronic structure is not one dimensional. Combining high-resolution resonant inelastic x-ray scattering experiments with theoretical model calculations, we show that (i) spin-orbital fractionalization occurs in CaCu_{2}O_{3} along the leg direction x through the xz orbital channel as in a 1D system, and (ii) no fractionalization is observed for the xy orbital, which extends in both leg and rung direction, contrary to a 1D system. We conclude that the directional character of the orbital hopping can select different degrees of dimensionality. Using additional model calculations, we show that spin-orbital separation is generally far more robust than the spin-charge separation. This is not only due to the already mentioned selection realized by the orbital hopping, but also due to the fact that spinons are faster than the orbitons.
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