Eur. Phys. J. Plus (2014) 129: 127
https://doi.org/10.1140/epjp/i2014-14127-x

Regular Article

Unusual ferromagnetism in Ising and Potts model on semi-directed Barabási-Albert networks

¹ Physics Department, Al-Aqsa University, P.O.4051, Gaza, Palestinian Authority
² Dietrich Stauffer Computational Physics Lab, Departamento de Física, Universidade Federal do Piauí, 64049-550, Teresina, Brazil

^* e-mail: msumoor@alaqsa.edu.ps

Received: 5 April 2014
Revised: 22 May 2014
Accepted: 23 May 2014
Published online: 23 June 2014

Abstract

We check the existence of a spontaneous magnetisation of Ising and Potts spins on semi-directed Barabasi-Albert networks by Monte Carlo simulations. We verify that the magnetisation for different temperatures T decays after a characteristic time τ(T), which we extrapolate to diverge at positive temperatures T _c (N) by a Vogel-Fulcher law, with T _c (N) increasing logarithmically with network size N.