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Temperature-induced Domain Shrinking in Dipolar Frustrated Ising Ferromangnet

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Abstract Book of the XXIII IUPAP International Conference on Statistical Physics, Genova, Italy, (9-13 July 2007)

Аннотация

Motivated by recent experimental observations on ultrathin Fe/Cu(001) films, we performed a theoretical analysis of magnetic domain pattern evolution in 2D Dipolar Frustrated Ising Ferromangnet. Patterns -of oppositely magnetized regions- arise from the competition between long-ranged dipolar interaction and nearest neighbor ferromagnetic exchange interaction. One well established experimental result is the domain size reduction with the increasing of the temperature, independently of the underlying pattern. For the ideal stripe pattern and under the Mean Field approximation, we found that the domain width ($h(T)$) decreases while the temperature is increased from $T=0$ to the Curie temperature ($T_C$); the two well known limits of $h$ for $T=0$ and $T_C$ are recovered continuously together with the expected shape of modulation (squared and cosine wave respectively). The lack of translational invariance, intrinsic in the pattern, implies that thermal fluctuations finally favor the dipolar interaction in its competition with the exchange interaction; this is the driving mechanism for domain shrinking, which is accompanied by the occurrence of a non-trivial magnetization profile at intermediate temperatures. Preliminary Monte Carlo results will be also discussed.

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