Resonances in a dilute gas of magnons and metamagnetism of isotropic   frustrated ferromagnetic spin chains
  We show that spin-S chains with SU(2)-symmetric, ferromagnetic nearest-neighbor and frustrating antiferromagnetic next-nearest-neighbor exchange interactions exhibit metamagnetic behavior under the influence of an external magnetic field for small S, in the form of a first-order transition to the fully polarized state. The corresponding magnetization jump increases gradually starting from an S-dependent critical value of exchange couplings and takes a maximum in the vicinity of a ferromagnetic Lifshitz point. The metamagnetism results from resonances in the dilute magnon gas caused by an interplay between quantum fluctuations and frustration. 
M. Arlego, F. Heidrich-Meisner, A. Honecker, G. Rossini, T. Vekua
cond-mat.str-el