%0 Journal Article
%T Orbital control of effective dimensionality: from spin-orbital fractionalization to confinement in the anisotropic ladder system CaCu2O3
%A Valentina Bisogni
%A Krzysztof Wohlfeld
%A Satoshi Nishimoto
%A Claude Monney
%A Jan Trinckauf
%A Kejin Zhou
%A Roberto Kraus
%A Klaus Koepernik
%A Chinnathambi Sekar
%A Vladimir Strocov
%A Bernd Buechner
%A Thorsten Schmitt
%A Jeroen van den Brink
%A Jochen Geck
%J Physics
%D 2013
%I arXiv
%R 10.1103/PhysRevLett.114.096402
%X 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 CaCu2O3, 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 CaCu2O3 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.
%U http://arxiv.org/abs/1310.8346v4