We study the fractional Schrödinger equations coupled with a neutral scalar fieldwhere (−∆) s and (I −∆) t denote the fractional Laplacian and Bessel operators with 3 4 < s < 1 and 0 < t < 1, respectively. Under some suitable assumptions for the external potentials V , K, and g, given q ∈ (1, 2) ∪ (2, 2 * s ) with 2 * s := 6 3−2s , with the help of an improved Fountain theorem dealing with a class of strongly indefinite variational problems approached by Gu-Zhou [Adv. Nonlinear Stud., 17 (2017), 727-738], we show that the system admits infinitely many nontrivial solutions.