New results on coupled Caputo-Hadamard fractional neutral differential equations supplemented by unbounded delays

This paper examines a new coupled system of nonlinear fractional differential equations involving sequential Caputo-Hadamard type fractional derivatives, Hadamard integrals, and unbounded delays. Qualitative theorems such as the existence and uniqueness of solutions are derived by applying Krasnoselskii's and Banach's fixed point techniques. Furthermore, we demonstrate the Hyers-Ulam (\(\text{H}\text{U}\)) and its generalized form of stability for the proposed system. The main results are illustrated through a practical example.