Modulational instability, quantum breathers and two-breathers in a frustrated ferromagnetic spin lattice under an external magnetic field Project supported by the National Natural Science Foundation of China (Grant No. 11604121), the Scientific Research Fund of Hunan Provincial Education Department, China (Grant Nos. 16B210 and 16A170), and the Natural Science Fund Project of Jishou University, China (Grant No. jdx17036). |
(color online) The magnon dispersion curves in the first Brillouin zone for the present zig-zag ferromagnetic chain with different values of the frustration parameter. The corresponding parameters are set to J = 1, a = 1, g = 1, μB = 1, S = 20, B = 50, and Δ = 2. |