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(a) Magnetic anisotropy energy and (b) magnetic moments for (001) FePt slabs and constrained bulk with fct L10 and bct B2 atomic structures. The number of slab atomic layers N and in-plane lattice parameter are varied. The vertical (at 3.87 Å) and horizontal dash-dot lines represent the corresponding values for completely relaxed bulk: “Bulk(L10).” The vertical dash-dot line at 4.33 Å indicates the lattice constant for which the lattice symmetry of constrained bulk is cubic rather than tetragonal: “Bulk(B2).”
Unit cell energy and volume, out-of-plane lattice parameter c, Poisson ratio, tetragonality c/a as function of in-plane lattice parameter in constrained bulk. The vertical dash-dot lines are the same as in Fig. 1.
Magnetic anisotropy energy dependence on the inverse number ofslab layers in case of four values of in-plane lattice parameter. 1/N = 0 corresponds to a constrained bulk (fixed in-plane lattice parameter and relaxed c/a ratio). Polynomial fits are used to connect the points.
Electronic density of states projected by spin (positive or negative values), by angular momentum (s, p, and d), and by site (Fe and Pt). “Constrained bulk” at three characteristic (DOS distinctive) values of in-plane lattice parameter a is presented. The bulk a = 3.87 represents the “dome”-region of MAE, whereas a = 3.1 and a = 4.3 are outside this region.
The same as in Fig. 1 but for nanocrystals of different shapes and number of atoms. The number of atoms not only enumerate the lower axis but is also shown as a label for each crystal in upper graph. The crystal diameter is shown at top axis. It is calculated as a diameter of the spherical particle with the same volume as a crystal at bulk lattice parameter.
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