Regensburg 2013 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 40: Poster Session Correlated Electrons
TT 40.57: Poster
Mittwoch, 13. März 2013, 15:00–19:00, Poster D
Quantum phases of a frustrated four-leg spin tube — Marcelo Arlego1, Wolfram Brenig2,3, •Yousef Rahnavard2,3, Björn Willenberg2,3, Hector Rosales1, and Gerardo Rossini1 — 1Departamento de Fisica, Universidad Nacional de La Plata, C.C. 67, 1900 La Plata, Argentina — 2Institute for Theoretical Physics, Technical University Braunschweig, D-38106 Braunschweig, Germany — 3Niedersächsische Technische Hochschule, NTH
We study the ground state phase diagram of a frustrated spin-1/2 four-leg tube. Using a variety of complementary techniques, namely density matrix renormalization group, exact diagonalization, Schwinger boson mean field theory, quantum Monte-Carlo and series expansion, we explore the parameter space of this model in the regime of all-antiferromagnetic exchange. In contrast to unfrustrated four-leg tubes we uncover a rich phase diagram. Apart from the Luttinger liquid fixed point in the limit of decoupled legs, this comprises several gapped ground states, namely a plaquette, an incommensurate, and an antiferromagnetic quasi spin-2 chain phase. The transitions between these phases are analyzed in terms of total energy and static structure factor calculations and are found to be of (weak) first order. Despite the absence of long range order in the quantum case, remarkable similarities to the classical phase diagram are uncovered, with the exception of the icommensurate regime, which is strongly renormalized by quantum fluctuations. In the limit of large leg exchange the tube exhibits a deconfinement cross-over from gapped magnon like excitations to spinons.