Uniqueness and Ulam–Hyers–Mittag–Leffler stability results for the delayed fractional multiterm differential equation involving the Φ-Caputo fractional derivative

The principal aim of this paper is to establish the uniqueness and Ulam–Hyers–Mittag–Leffler (UHML) stability of solutions for a new class of multiterm fractional time-delay differential equations in the context of the Φ-Caputo fractional derivative. To achieve this purpose, the generalized Laplace transform method alongside facet with properties of the Mittag–Leffler functions (M–LFs) are utilized to give a new representation formula of the solutions for the aforementioned problem. Besides that, the uniqueness of the solutions of the considered problem is also proved by applying the well-known Banach contraction principle coupled with the Φ-fractional Bielecki-type norm, while the Φ-fractional Gronwall type inequality and the Picard operator (PO) technique, combined with the abstract Gronwall lemma, are used to prove the UHML stability results for the proposed problem. Lastly, an example is offered to assure the validity of the obtained theoretical results.