Ferromagnetic films

E. Pugh and T. O. Mohr, Thin Films Properties of Ferromagnetic Films, ASM, Metals Park, Ohio, 1963, Chapt. 7. 

After the discovery of the oscillatory magnetic interlayer coupling between ferromagnetic films separated by a paramagnetic spacer these sandwiched systems have been a subject of intense research. There have been many attempts to explain the magnetic interlayer coupling and a great number of theoretical and experimental studies have been performed . ... 

Julliere M (1975) Tunneling between ferromagnetic films. Phys Lett 54A 225-226... 

The profile Bz(x, y) is determined by the ratio of two length scales thickness of a ferromagnetic film D and distance between the domain walls w (hereafter we consider the width of the domain wall to be much less than ). Provided the ferromagnetic film is rather thick (D w), the magnetic... 

The results show that the attenuation length of minority electrons in NiFe and CoFe is only about 1 nm, while that of majority electrons is a factor 4 to 6 larger. Consequently, thin ferromagnetic films act as efficient spin filters for hot electron currents. For example, the calculated transmission polarization of a 4 nm thick ferromagnetic film with Ai = 1 nm and At = 5 nm amounts already 92%. 

Table 7.10. Selected highlights of the PLD of (1) p-type ZnO films, including pn-junctions, (2) n-type ZnO films on various substrates, and (3) ferromagnetic films...

R. von Helmolt, J. Wecker, B. Holzapfel, L. Schultz, and K. Samwer, Giant negative magnetoresistance in perovskite-like La2/2Ba, /,MnOv ferromagnetic films, Phys. Rev Lett. 71 2331-2333 (1993). 

Neutron reflectometry has been applied to the study of a variety of surfaces, including solid polymeric films, ferromagnetic films, and pure liquid surfaces (Penfold and Thomas, 1990). The technique has also been used in conjunction with Langmuir film balance apparatus to study the adsorption of compounds at the air-water interface, e.g., alkyl trimethylammonium bromide surfactants (Lee et al., 1989), fatty acids (e.g., Grundy et al., 1988), and a variety of polymeric compounds (e.g., Henderson et al., 1991 Henderson, 1993). 

Both of the above problems can be solved in S-FNF-S junctions, in which supercurrent flows in the direction parallel to the FN interface of the composite weak-link region. S-FNF-S junction consists of a normal metal film that is sandwiched between two ferromagnetic films. The superconducting electrodes are joined to the end-walls of such an FNF multilayer structure. In [33-35] it was... 

Fig. 7.2. Scheme of an exchange coupled system. Ferromagnetic films interact via interlayer coupling (/) across paramagnetic layers. / describes the interlayer coupling that is responsible for the ferromagnetic order within each layer. 

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... 

Due to the potential application of ultra-thin ferromagnetic films for spintronic devices, [2005Pra] studied the growth characteristics of thin layers of Coi Fex on a W (1 10) substrate. Although a homogeneous random monolayer was produced, annealing at intermediate temperatures (237°C) gave SRO FeaCo and FeO supers tmetures. 

There are many theoretical approaches for the description of ferromagnetic films, nanoparticles and nanogranular ceramics. The comprehensive reference to the multitude of above theoretical methods can be found in preceding Sect. 2.2.2. Below we will draw attention to the superparamagnetism and its anomalous properties. The consideration will be carried out on the base of the paper [111]. 

FIGURE 7 Scheme of ferromagnetic film for investigation of the local magnetic susceptibility along directions 1-1,2-2 and 3-3 dotted line - the middle of the film. 

Measurements of the dependences F - 1 were provided with using of the ferromagnetic film, the scheme of which is presented in the Fig. 7. 

Applications. Thin (Sm, Pr, Ce, Nd, Y)Co65-s5 ferromagnetic films have been manufactured by Harada et al. (1988) useful for recording materials and miniature motors. Miyamoto and Tazaki (1985) have fabricated magnetic discs, cards or tapes with Smi-j C0 c films deposited by coevaporation onto poljdmide substrates. 

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