Magnetic thickness dependence

Fig. 9. Magnetic field dependence of the magnetization at selected temperatures for a 150-nm thick Ga xMn As film with a Mn composition x = 0.03S. The magnetic field is applied parallel to the sample surface (direction of magnetic easy axis) except for the closed circles at 5 K taken in perpendicular geometry. The solid line for S K shows the magnetization determined from transport measurements. The upper left inset shows a magnified view of the magnetization in the parallel field at 5 K. The lower right inset shows the temperature dependence of the remanent magnetization (Ohno et al. 1996a).

Fig. 16. Magnetic field dependence of the resistivity for a 200-nm thick film of Ga Mn.t As with x = 0.053 in the high-temperature paramagnetic region. The solid lines show the fitting using eq. (2) (Omiya et al. 2000).

Fig. 19. Magnetic field dependence of the diagonal resistivity p (open circles) and magnetization Afnaii (close circles) determined from the ratio of the Hall and diagonal resistivities, Afnall = PHM/CP< where c = 6.3, for a 1.3-rrm thick film of lni tMnr As with x = 0.013. The solid line is a fit by the modified Brillouin function B (y), where S = 5/2 and y = SgpgB/(T + T0) with T0 = 1.5 K. The inset shows the hysteresis observed in the Hall resistivity at 3.5 K (Ohno et al. 1992).

Fig. 29. Thickness dependence of Che ratio of Hall resistance and sheet resistance ftHall/ sheei> which is proportional to magnetization perpendicular to the film plane, as a function of the magnetic field at 10 K. The inset shows the thickness dependence of 7c (Matsukura et al. 1998a).

Here, we employ examples primarily from the magnetic recording industry to show how the physics of nano-films is derived from the properties of bulk liquids through the thermodynamics of interaction with the solid surface. The nano-film spreading rate is derived from the film thickness dependence of the surface energy. The nano-film viscosity is related to the nano-film vapor pressure, both of which increase... 

The magnetic properties of the single ferromagnetic films present in our structures have been intensively investigated [16]. The magnetization measurements do not reveal any thickness dependence of the Curie temperature, Tburie, in the thickness range of dF = 3.3 - 70 nm. It is known, in fact, that rCurie may be a function not only of the Ni content [19], but also of the film thickness... 

Interesting thickness dependence of saturation magnetization Ms has been observed in ZnO films on AI2O3 substrate and MgO on Si substrate [5, 17-19]. 

Figure 18.29 (a) Thickness dependence of saturated magnetization (b) Magnetoelectric effect in a 70 nm thin film of BiFe03. From Ref [161],... 

Fig. 12. (a) Temperature dependence of the basal-plane magnetization of Gd films of various thickness. The applied field is 50 Oe in each case (b) the thickness dependences of the Curie-Weiss temperature Tp and spin-glass temperature T.. At low coverage, both temperatures increase as powers of the film thickness. 

Layer-thickness dependence of magnetic properties at room temperature... 

Layer-thickness dependence of magnetic properties at room temperature. Figure 9a (Shan and Sellmyer 1990b) shows a detailed Fe layer-thickness dependence of hysteresis loops for 5 A DylX A Fe as the Fe layer thickness varies from 2.5 A to 40 A note especially that the interval is only 1.25 A asX ranges from 2.5 to 10 A. The layer-thickness dependences of magnetization and anisotropy determined from fig. 9a are summarized in fig. 10. 

Several results about the magnetization can be found from figs. 9a and 10. To understand the layer-thickness dependence of magnetization, both the antiferromagnetic coupling of Dy and Fe moments and the modulated distribution of composition have to be taken into account, (i) Sample 5 ADy/6.25 AFc is in a state close to the compensation point the Dy moment dominates for X <6.5 A and the Fe moment dominates for X > 6.5 A. (ii) As X increases from 2.5 to 6.5 A, the magnetization magnitude of Dy/Fe,... 

Fig. 10. Fe layer-thickness dependence of magnetization and measured anisotropy for 5 A Dy/JT A Fe at 300K (after Shan and Selhnyer 1990b).

Figure 9b (Shen 1994) shows the Dy layer-thickness dependence of hysteresis loops of T A Dy/5 A Fe as the Dy layer thickness varies from 6.5 A to 5 A note especially (i) although the thickness interval is only 0.5 A, the coercivity and magnetization are very strongly dependent on thickness as the Dy layer thickness Y approaches 5 A where sample 5 A Dy/5 A Fe is in a state close to the compensation point, (ii) Compared with the loops in fig. 9a, the loops in fig. 9b illustrate much better squareness because these samples were coated with a 500 A SiO layer to protect fi om oxidation.

Fig. 14. Three-dimensional diagram of layer-thickness dependence of magnetization for YkDylXACo at 8kOe and 300 K (after Shan and Sellmyer 1990b).

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