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arXiv · 1205.1954

Spin-Orbital Separation in the quasi 1D Mott-insulator Sr2CuO3

J. Schlappa·K. Wohlfeld·K. J. Zhou·M. Mourigal·M. W. Haverkort·V. N. Strocov·L. Hozoi·C. Monney·S. Nishimoto·S. Singh·A. Revcolevschi·J. -S. Caux·L. Patthey·H. M. Rønnow·J. van den Brink·T. Schmitt
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Abstract

As an elementary particle the electron carries spin \hbar/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[1]. The hallmark of one-dimensional (1D) physics is a breaking up of the elementary electron into its separate degrees of freedom[2]. The separation of the electron into independent quasi-particles that carry either spin (spinons) or charge (holons) was first observed fifteen years ago[3]. 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.

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J. Schlappa, K. Wohlfeld, K. J. Zhou, M. Mourigal, M. W. Haverkort, V. N. Strocov, L. Hozoi, C. Monney, S. Nishimoto, S. Singh, A. Revcolevschi, J. -S. Caux, L. Patthey, H. M. Rønnow, J. van den Brink, T. Schmitt. 2012-05-09. Spin-Orbital Separation in the quasi 1D Mott-insulator Sr2CuO3. https://doi.org/10.1038/nature10974

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