Giant moments

Alloys of iridium and platinum with similar small amounts of iron also exhibit enhancement effects and a giant moment in the case of iron in platinum and platinum-rich alloys as shown in Figure 5 (18). 

The EPR of 3d probes in metals is unusual. There are some exceptions e.g. Cu Mn (Owen et al. 1956), Pd Mn (Alquie et al. 1978) and Pd Fe (Devine 1976, 1977). But already in the last example the author pointed out that the observation of a resonance does not enable one to deduce whether this resonance simply originates from Fe or fiom Fe plus a spin-polarized cloud which is responsible for the formation of the well-known giant moment in the system Pd Fe. The reader may find further examples of 3d EPR signals in metals in the review articles by Taylor (1975) and by Elschner and Loidl (1997). 

We consider a lattice of crystal-field split ions in which some of the ions are replaced by impurities. These impurities can be either other RE-ions with different crystal-field splitting and/or different coupling parameter to the neighbouring ions or they can be ions such as La which act like holes in the lattice due to the absence of 4f electrons. In the following we want to discuss the influence of such impurities on the properties of the otherwise perfect lattice system. We shall divide the problem into two parts. First we shall consider the one impurity problem. Here the changes of the excitation spectrum are of interest (local modes, resonant modes) as well as the possible occurrence of such phenomena as giant moments or giant Jahn-Teller distortions. After this we consider finite impurity concentrations and their effect on the transition temperature. 

Figure 4 Giant Magnetoconductance. The change in the non-local layer dependent conductivity between parallel and anti-parallel alignment of the cobalt moments. For this case of strong scattering in both the cobalt and copper, contributions to the GMR come from electrons that are accelerated in one cobalt layer and contribute to the current in the other.

Here, yc stands for the (giant) magnetic moment of the cluster which replaces the "y" for single. Isolated paramagnetic spins k is the Boltzmann constant. 

What happened next was nothing less than a turn of events that would propel us into another world. For with the fading of the radio Dennis gave forth, for a few seconds, a very machine-like, loud, dry buzz, during which his body became stiff After a moment s silence, he broke into a frightened series of excited questions. "What happened " and, most memorably, "I don t want to become a giant insect "... 

Let us review all this. At an age of 12 billion years, the yellow dwarf will mutate into a red giant with 100 times the radius. This in turn will give way to a vaporous cloud with a very small white object at its centre. When the yellow dwarf has handed over to the white dwarf, the solar pageant will be close to an end. But for the moment, the Sun still shines staunchly. 

Once indoors, I could sup deep in horror with Macbeth, or exult like a mystic in the oneness of eternity, or wallow in jewels like Shy-lock, but at least I only had to open my eyes to be comparatively safe. Not as safe as I would like to have been, as it was particularly difficult to get accustomed to the changes in body image. At one moment I would be a giant in a tiny cupboard, and the next, a dwarf in a huge hall. It is difficult enough to explain what it feels like to have been Gulliver, or Alice in Wonderland, in the space of a few... 

Atomic core polarization e -p correlation Yamazaki and Ohtsuki [5] emphasized the important role of a special type of configuration mixing which contributes to a substantial reduction of the radiative transition rate. This effect is essentially the same as in the nuclear core polarization phenomena, where low energy transition moments are affected by the presence of high excitation mode (giant resonances). In the present case, the low energy El transitions ( 2 eV) are retarded by a factor of 3 by the existence of the hard electronic excitation ( 20 eV). 

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