Transition metal amorphous alloys magnetic properties

A common feature of R-amorphous alloys and transition metal-metalloid alloys is that they show similar transport properties such as high resistivities with weak temperature dependence and often at low temperature a logarithmic variation with temperature (Kastner et al., 1980). The magnetic R-alloys often show additional transport behaviour. We will now discuss this in detail for several R-amorphous alloys. 

Bellissent, R., Galli, G., Hyeon, T., MigUaido, R, Parette, G., Suslick, K.S. Magnetic and structural properties of amorphous transition metals and alloys. J. Non-Cryst. Solids 205-207, 656-659 (1996)... 

Solid-state nuclear magnetic resonance (NMR) has been extensively used to assess structural properties, electronic parameters and diffusion behavior of the hydride phases of numerous metals and alloys using mostly transient NMR techniques or low-resolution spectroscopy [3]. The NMR relaxation times are extremely useful to assess various diffusion processes over very wide ranges of hydrogen mobility in crystalline and amorphous phases [3]. In addition, several borohydrides [4-6] and alanates [7-11] have also been characterized by these conventional solid-state NMR methods over the years where most attention was on rotation dynamics of the BHT, A1H4, and AlHe anions detection of order-disorder phase transitions or thermal decomposition. There has been little indication of fast long-range diffusion behavior in any complex hydride studied by NMR to date [4-11]. 

In this chapter we present a survey of our current understanding of interrelations between the electronic and ionic structure in late-transition-polyvalent-element metallic glasses. Evidence of a strong influence of conduction electrons on the ionic structure, and vice versa, of the ionic structure on the conduction electrons, is presented. We discuss as well the consequences to phase stability, the electronic density of states, dynamic properties, electronic transport, and magnetism. A scaling behaviour of many properties versus Z, the mean electron number per atom, is the most characteristic feature of these alloys. Crystalline alloys which are also strongly dominated by the conduction electrons are often called electron phases or Hume-Rothery phases. The amorphous alloys under consideration are consequently described as an Electron Phase or Hume-Rothery Phase with Amorphous Structure. Similar theoretical concepts as applied to crystalline Hume-Rothery alloys are used for the present amorphous samples. 

Several aspects of the magnetic properties of amorphous alloys composed of rare earths and transition metals have already been discussed by Rhyne (1979) in Volume 2, Chapter 16 of this Handbook. It is difficult to avoid overlap completely, although we shall attempt to focus mainly on supplementary experimental information that has become available in the meantime. 

The objective of this chapter is to focus on the magnetostrictive J Fe2 alloys. For a broad review of the magnetic properties of rare earth-transition metal alloys, the reader is referred to ch. 14 of this handbook. Chapter 16 deals specifically with rare earth alloys in the amorphous form. Earlier comprehensive reviews of the structural and magnetic properties of the rare earth-transition metal compounds are also available, e.g. Taylor (1971), Rhyne and McGuire (1972)/Wallace (1973). 

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