Absence of ferromagnetism in Ising model on directed Barabasi-Albert   network
  With up to 7 million spins, the existence of spontaneous magnetization of Ising spins on directed Barabasi-Albert networks is investigated by Monte Carlo simulations. We confirm our earlier result that the magnetization for different temperatures T decays after a characteristic time tau(T), which we extrapolate to diverge at zero temperature by a modified Arrhenius law,or perhaps a power law. 
Muneer A. Sumour, M.M. Shabat, D. Stauffer