Schedule Oct 12, 2012
Quantum Phases of Frustrated Spin-S Chains in an External Magnetic Field Close to Saturation
F. Heidrich-Meisner (LMU Munich)

Authors: F. Heidrich-Meisner (LMU Munich, Germany), M. Arlego (University of La Plata, Argentina), A. Honecker (U Goettingen, Germany), S. Greschner (U Hannover), A. Kolezhuk (University of Kiev, Ukraine),  G. Rossini (University of La Plata, Argentina), T. Vekua (U Hannover, Germany)

We map out the ground states of frustrated spin-S chains in a strong magnetic field in the immediate vicinity of full saturation, using both a mapping to a dilute two-component Bose gas and density matrix renormalization group simulations. For ferromagnetic nearest-neighbor and frustrating antiferromagnetic next-nearest-neighbor exchange interactions, the generic feature is metamagnetic behavior for small S>1/2 [1], in the form of a first-order transition to the fully polarized state. The magnetization jump increases gradually starting from an S-dependent critical value of exchange couplings until the ferromagnetic Lifshitz point is reached. The metamagnetism results from resonances in the dilute magnon gas caused by an interplay between quantum fluctuations and frustration. In the case of antiferromagnetic nearest-neighbour-interactions we demonstrate the existence of a two-component Luttinger liquid phase leading to series of phase transitions between that phase, a chiral phase, and another one-component Luttinger liquid [2].

[1] M. Arlego, F. Heidrich-Meisner, A. Honecker, G. Rossini, T. Vekua
    Phys. Rev. B 84, 224409 (2011)

[2] A. K. Kolezhuk, F. Heidrich-Meisner, S. Greschner, T. Vekua, Phys. Rev. B 85, 064420 (2012)

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