Temperature-Induced Domain Shrinking in Ising Ferromagnets Frustrated by a Long-Range Interaction

Abstract. We investigate a spin model in which a ferromagnetic shortrange interaction competes with a long-range antiferromagnetic interaction decaying spatially as 1 rd+ , d being the dimensionality of the lattice. For 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 = 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 ap...

• Type: Journal
• Year: 2009
• Where: COMPLEX
• Authors: Alessandro Vindigni, Oliver Portmann, Niculin Saratz, Fabio Cinti, Paolo Politi, Danilo Pescia
• Keywords: COMPLEX 2009, Ferromagnetic Shortrange Interaction, Long-range Antiferromagnetic Interaction, Theoretical Computer Science, Uniformly Magnetized State