147 research outputs found

    Temperature dependence of the coercive field in single-domain particle systems

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    The magnetic properties of Cu97Co3 and Cu90Co10 granular alloys were measured over a wide temperature range (2 to 300K). The measurements show an unusual temperature dependence of the coercive field. A generalized model is proposed and explains well the experimental behavior over a wide temperature range. The coexistence of blocked and unblocked particles for a given temperature rises difficulties that are solved here by introducing a temperature dependent blocking temperature. An empirical factor gamma arise from the model and is directly related to the particle interactions. The proposed generalized model describes well the experimental results and can be applied to other single-domain particle system.Comment: 7 pages, 8 figures, revised version, accepted to Physical Review B on 29/04/200

    Poincar\'e and sl(2) algebras of order 3

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    In this paper we initiate a general classification for Lie algebras of order 3 and we give all Lie algebras of order 3 based on sl(2,C)\mathfrak{sl}(2,\mathbb C) and iso(1,3)\mathfrak{iso}(1,3) the Poincar\'e algebra in four-dimensions. We then set the basis of the theory of the deformations (in the Gerstenhaber sense) and contractions for Lie algebras of order 3.Comment: Title and presentation change
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