Berlin 2008 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 8: Correlated Electrons: Spin Systems and Itinerant Magnets 1
TT 8.13: Vortrag
Montag, 25. Februar 2008, 17:30–17:45, H 0104
Spinon confinement and the Haldane gap in SU(n) spin chains: numerical studies — •Max Führinger1, Stephan Rachel1, Ronny Thomale1, Peter Schmitteckert1,2, and Martin Greiter1 — 1Institut für Theorie der Kondensierten Materie, Universität Karlsruhe, 76128 Karlsruhe — 2Institut für Nanotechnologie, Forschungszentrum Karlsruhe, 76021 Karlsruhe
Recently, two of us [1] motivated a general set of rules which SU(n) spin chains exhibit spinon confinement and hence a Haldane gap in the spectrum. According to these rules, models of spin chains with SU(n) spins transforming under a representation corresponding to a Young tableau consisting of a number of boxes λ which is divisible by n, are gapped. If λ and n have no common divisor, the spin chain will support deconfined spinons and not exhibit a Haldane gap. If λ and n have a common divisor different from n, it will depend on the specifics of the model including the range of the interaction.
Here we present numerical evidence for these rules, obtained by exact
diagonalization and DMRG, using the representations 3,
6, 8, and 10 of SU(3) and
the representations 4, 6, and
10 of SU(4). The numerical data obtained include the
low energy spectra and results for bond and entanglement
entropies. The entanglement entropy yields the central charge
of the critical models as well.
[1] M. Greiter and S. Rachel, Phys. Rev. B 76, 184441 (2007).