Metamagnetism in frustrated ferromagnetic spin S chains

ARLEGO MARCELO; HEIDRICH-MEISNER FABIAN; HONECKER ANDREAS; ROSSINI GERARDO; VEKUA TEMOURAZ

Montevideo

Congreso; Segunda reunión conjunta Sociedad Uruguaya de Física - Asociación de Física Argentina; 2011

We show that frustrated, SU (2)-symmetric spin-S chains with ferromagnetic nearest-neighbor interactions exhibit metamagnetic behavior under the influence of an external magnetic field for small S ≥ 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 and takes a maximum in the vicinity of a Lifshitz point. The metamagnetism results from resonances in the dilute magnon gas caused by an interplay between quantum fluctuations and frustration. Our predictions are verified numerically byprecise density matrix renormailzation group (DMRG) and exact diagonalization (ED) calculations on S = 1, 3/2, 2 systems.