  It was reported that Kerr-Newman black holes can support linear charged
scalar fields in their exterior regions. These stationary massive charged
scalar fields can form bound states, which are called stationary scalar clouds.
In this paper, we show that Kerr-Sen black holes can also support stationary
massive charged scalar clouds by matching the near- and far-region solutions of
the radial part of the Klein-Gordon wave equation. We also review stationary
scalar clouds within the background of static electrically charged black hole
solutions in the low-energy limit of heterotic string field theory, namely, the
Gibbons-Maeda-Garfinkle-Horowitz-Strominger black holes.
