Abstract
By employing the concurrence, we investigate the dynamics of entanglement between two atoms in a double two-photon Jaynes-Cummings model when the cavity field is previously in a maximally entangled state. The influence of the atomic coherence on the time evolution of the atom-atom entanglement is examined. It is shown that the phenomenon of the sudden birth of entanglement occurs, and the atomic coherence decreases the degree of the atom-atom entanglement. Moreover, it is found that a maximally entangled two-atom state can be generated.