Dresden 2009 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 12: Correlated Electrons: Spin Systems and Itinerant Magnets 2

TT 12.3: Vortrag

Montag, 23. März 2009, 14:30–14:45, HSZ 304

The frustrated ferromagnetic S=1/2 Heisenberg chain in a magnetic field – How multipolar spin correlations emerge from magnetically ordered states — Julien Sudan¹, Andreas Lüscher¹, and •Andreas M. Läuchli² — ¹IRRMA, EPF Lausanne, Switzerland — ²MPI für Physik komplexer Systeme, Dresden, Germany

We present the phase diagram of the frustrated ferromagnetic S=1/2 Heisenberg J₁-J₂ chain in a magnetic field, obtained by large scale exact diagonalizations and density-matrix-renormalization-group simulations. A vector chirally ordered state, metamagnetic behavior and a sequence of spin multipolar Luttinger liquid phases up to hexadecupolar order are found. Starting from classical considerations, we point out that various multipolar correlations are imprinted in a magnetic state and that they can survive the onset of frustration and quantum fluctuations which destroy the convention al magnetic order. Our results also shed new light on previously discovered spin multipolar phases in two-dimensional S=1/2 quantum magnets in a magnetic field. We conclude by presenting numerical results on the dynamical spin structure factor in the various phases which are valuable in identifying multipolar phases in experiments.