Suppression of Quantum Phase Interference in Molecular Magnets Fe&#8328;   with Dipolar-Dipolar Interaction
  Renormalized tunnel splitting with a finite distribution in the biaxial spin model for molecular magnets is obtained by taking into account the dipolar interaction of enviromental spins. Oscillation of the resonant tunnel splitting with a transverse magnetic field along the hard axis is smeared by the finite distribution which subsequently affects the quantum steps of hysteresis curve evaluated in terms of the modified Landau-Zener model of spin flipping induced by the sweeping field. We conclude that the dipolar-dipolar interaction drives decoherence of quantum tunnelling in molcular magnets Fe&#8328;, which explains why the quenching points of tunnel spliting between odd and even resonant tunnelling predcited theoretically were not observed experimentally. 
Zhi-De Chen, J.-Q. Liang, and Shun-Qing Shen