09. Jan. 2014, 16:15 Uhr, Gebäude NW1, Raum H3
Spin-Orbital Separation in the quasi 1D Mott-insulator Sr2CU03
Prof. Dr. Jeroen van den Brink , IFW Dresden
As an elementary particle the electron carries spin ħ/2 and charge e. When binding to the atomic nucleus it also acquires an angular momentum quantum number corresponding to the quantized atomic orbital it occupies (e.g., s, p or d). Even if electrons in solids form bands and delocalize from the nuclei, in Mott insulators they retain their three fundamental quantum numbers: spin, charge and orbital. The hallmark of one-dimensional (1D) physics is a breaking up of the elementary electron into its separate degrees of freedom. The separation of the electron into independent quasi-particles that carry either spin (spinons) or charge (holons) was first observed fifteen years ago. Using Resonant Inelastic X-ray Scattering on the 1D Mott-insulator Sr2CuO3 we now observe also the orbital degree of freedom separating. We resolve an orbiton liberating itself from spinons and propagating through the lattice as a distinct quasi-particle with a substantial dispersion of ~0.2 eV.
J. Schlappa et al, Nature 485, 82 (2012)