What is it about?
We report a theoretical investigation of new magnetic phases of thin dysprosium films. At the surfaces, the balance between exchange and anisotropy energies favors the alignment of spins along the basal plane easy axis directions. Near the Curie temperature, the helimagnetic phase is strongly modified, allowing surface spins to lock into the basal plane anisotropy easy directions. As the temperature raises, we find transitions to other surface lockin patterns, which are tunable by external field strengths of a few hundred milli-Oersteds.
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Why is it important?
Considerable research effort has been dedicated to investigate the impact of confinement and surface effects on the equilibrium phases of magnetic systems with size comparable to fundamental magnetic lengths. Particularly interesting are magnetic systems in which the bulk magnetic phases consist of a periodical repetition of units containing a finite number of spins. This is the case of the helical structure of rare earth metals, and the helix period is a valuable length scale to evaluate confinement effects.
Perspectives
he rare-earth (RE) elements exhibit a reach variety of magnetic phases, either induced by external magnetic fields or by thermal effects. Finite-size and surface effects add new features leading to new magnetic phases of thin films [1, 2, 3, 4]. In this paper, we present a theoretical discussion of new magnetic phases of thin dysprosium films. These phases are associated to the lockin of surface spins to the easy axis directions in the basal plane (see Fig. 1 for typical patterns). They resemble the spin slip phases of Ho, in the sense that they originate from the prevalence of the anisotropy energy over the exchange energy. Also, as the temperature raises there is a sequence of surface lockin phases, each within a finite temperature interval, with surface pinning to different easy directions in the basal plane.
Fabio Sales
Instituto Federal de Educacao Ciencia e Tecnologia do Maranhao
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This page is a summary of: Surface spin slips in thin dysprosium films, Journal of Materials Science, April 2010, Springer Science + Business Media,
DOI: 10.1007/s10853-010-4467-7.
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