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arXiv · 1701.07648

Microscopic Aspects of Magnetic Lattice Demagnetizing Factors

Mikael Twengström·Laura Bovo·Michel J. P. Gingras·Steven. T. Bramwell·Patrik Henelius
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Abstract

The demagnetizing factor N is of both conceptual interest and practical importance. Considering localized magnetic moments on a lattice, we show that for non-ellipsoidal samples, N depends on the spin dimensionality (Ising, XY, or Heisenberg) and orientation, as well as the sample shape and susceptibility. The generality of this result is demonstrated by means of a recursive analytic calculation as well as detailed Monte Carlo simulations of realistic model spin Hamiltonians. As an important check and application, we also make an accurate experimental determination of N for a representative collective paramagnet (i.e. the Dy2Ti2O7 spin ice compound) and show that the temperature dependence of the experimentally determined N agrees closely with our theoretical calculations. Our conclusion is that the well established practice of approximating the true sample shape with "corresponding ellipsoids" for systems with long-range interactions will in many cases overlook important effects stemming from the microscopic aspects of the system under consideration.

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Mikael Twengström, Laura Bovo, Michel J. P. Gingras, Steven. T. Bramwell, Patrik Henelius. 2017-09-27. Microscopic Aspects of Magnetic Lattice Demagnetizing Factors. https://doi.org/10.1103/physrevmaterials.1.044406

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