Probing Higgs sectorCPviolation with top quarks at a photon linear collider

We investigate for two Higgs-doublet models with intrinsic {ital CP} violation in the scalar potential {ital CP}-nonconserving effects in unpolarized {gamma}{gamma}{r_arrow}{ital t{bar t}} for a range of neutral Higgs boson masses which includes resonant {ital cphi} production and the subsequent decay of {ital cphi}{r_arrow}{ital t{bar t}}. The importance of taking into account, even in the resonant case, the interference with the nonresonant background is shown. Further, we propose and calculate three asymmetries which efficiently trace {ital CP}-violating effects in {gamma}{gamma}{r_arrow}{ital t{bar t}} using semileptonic {ital t{bar t}} decays.