Discrete modulational instability and bright localized spin wave modes in easy-axis weak ferromagnetic spin chains involving the next-nearest-neighbor coupling

Xie Jiayu¹, Deng Zhihao¹, Chang Xia¹, Tang Bing^{1, 2, †}

Modulational instability regions (bright zone) on the (q,Q) plane for different values of γ: (a) 0, (b) 0.2, (c) 0.3, (d) 0.5. The relevant parameters include D = 0, J = 1, S = 10, a = 1, A = 10, and α 0 = 0.3 .