We investigate a spin model in which a ferromagnetic short-range interaction competes with a long-range antiferromagnetic interaction decaying spatially as 1+ , d being the dimensionality of the lattice. For σ smaller than a certain threshold ̂ (with ̂ >1 ), the long-range interaction is able to prevent global phase separation, the uniformly magnetized state favored by the exchange interaction for spin systems. The ground state then consists of a mono-dimensional modulation of the order parameter resulting in a superlattice of domains with positive and negative magnetization. We find that the period of modulation shrinks with increasing temperature T and suggest that this is a universal property of the considered model. For d = 2 and σ= 1 (dipolar interaction) Mean-Field (MF) calculations find a striking agreement with experiments performed on atomically-thin Fe/Cu(001) films. Monte Carlo (MC) results for d = 1 also support the generality of our arguments beyond the MF approach.
Temperature-induced domain shrinking in ising ferromagnets frustrated by a long-range interaction / Vindigni A.; Portmann O.; Saratz N.; Cinti F.; Politi P.; Pescia D.. - ELETTRONICO. - 4:(2009), pp. 783-786. (Intervento presentato al convegno 1st International Conference on Complex Sciences: Theory and Applications, Complex 2009) [10.1007/978-3-642-02466-5_76].
Temperature-induced domain shrinking in ising ferromagnets frustrated by a long-range interaction
Cinti F.Membro del Collaboration Group
;
2009
Abstract
We investigate a spin model in which a ferromagnetic short-range interaction competes with a long-range antiferromagnetic interaction decaying spatially as 1+ , d being the dimensionality of the lattice. For σ smaller than a certain threshold ̂ (with ̂ >1 ), the long-range interaction is able to prevent global phase separation, the uniformly magnetized state favored by the exchange interaction for spin systems. The ground state then consists of a mono-dimensional modulation of the order parameter resulting in a superlattice of domains with positive and negative magnetization. We find that the period of modulation shrinks with increasing temperature T and suggest that this is a universal property of the considered model. For d = 2 and σ= 1 (dipolar interaction) Mean-Field (MF) calculations find a striking agreement with experiments performed on atomically-thin Fe/Cu(001) films. Monte Carlo (MC) results for d = 1 also support the generality of our arguments beyond the MF approach.
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