  We investigate gravitational waves (GWs) generated in a two-field
inflationary model with a non-canonical kinetic term, in which the
gravitational Chern-Simons term is coupled to a heavy dynamical field. In such
a model, primordial GWs experience a period of resonant amplification for some
modes. In addition, isocurvature perturbations suffer from a temporary
tachyonic instability due to an effective negative mass, which source curvature
perturbations, resulting in large induced GWs. These two stochastic
gravitational wave backgrounds correspond to different frequency bands, which
are expected to be detected by future GW detectors such as SKA, LISA and Taiji.
