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).

Su Wanhan, Xie Jiayu, Wu Tianle, Tang Bing
       

(color online) The growth rate (gain) of the instability versus the perturbation wave number for various values of λ. The main parameters are the same as those in Fig. 1.