Figure 4 - uploaded by Giovanni Manfredi
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Total magnetization M tot , from Eq. (10), as a function of temperature, for a cobalt (left), iron (right) or nickel (middle) nanowire with dimensions 50 nm×50 nm×50 nm. The different symbols stand for different time steps ∆t = 2.5 fs (green crosses), 5 fs (red circles), and 10 fs (blue crosses). The computational grid size is ∆x = 1 nm. The black vertical dash-dotted lines represent the bulk Curie temperatures as given in Table 1.

Total magnetization M tot , from Eq. (10), as a function of temperature, for a cobalt (left), iron (right) or nickel (middle) nanowire with dimensions 50 nm×50 nm×50 nm. The different symbols stand for different time steps ∆t = 2.5 fs (green crosses), 5 fs (red circles), and 10 fs (blue crosses). The computational grid size is ∆x = 1 nm. The black vertical dash-dotted lines represent the bulk Curie temperatures as given in Table 1.

Contexts in source publication

Context 1
... slight discrepancy starts occurring for iron at ∆x = 5 nm. Figure 4 shows the dependence of the numerical results with respect to the time step ∆t, again for cubic nano-objects of side 50 nm, with computational cell size ∆x = 1 nm. The final time is always t f = 50 ps, so that the number of time steps is N = 5 × 10 3 for ∆t = 10 fs (blue curve), N = 10 4 for ∆t = 5 fs (red curve), and N = 2 × 10 4 for ∆t = 2.5 fs (green curve). ...
Context 2
... One should further keep in mind that, without the temperature scaling adopted here and detailed in Sec. 2.3, the error on T C would be much higher, possibly one order of magnitude [13]. The values we obtain are thus a good trade-off between accuracy and computational efficiency. We also note that the experimental bulk values of T C displayed on Fig. 4 as vertical lines are given for reference, but never used in practice to determine the size effects. Instead, the effective "bulk" values of T C that we use are those obtained computationally with the largest structure that we consider (see Sec. 5 for details). ...