Kondo materials

CeNiSn. Due to its quite unusual properties, this Kondo material has been the subject of an intense research effort for over a decade, using practically all relevant physical methods. Unfortunately, transport, caloric, and bulk magnetic data are aU quite sensitive to impurities. Consequently, the picture regarding the electronic structure of CeNiSn changed over the years. The original woik has been reviewed extensively ly Takabatake and Fujii (1993). The more recent results, based on samples of improved quality are described in Takabatake et al. (1996). 

The same study (Neville et al. 1996) also reports on inelastic neutron scattering measurements. They show spin wave excitation at low temperatures which, however, collapse into a diffusive response at 10 K (see in this connection also the discussion on USb). The 10 K point is clearly a special temperature but its exact nature remains enigmatic. But without doubt, this Kondo material exhibits most imusual spin d3mamical properties. Further studies are called for. 

Fig. 5.23. Possible outcomes of accretion on to a CO white dwarf, according to its mass and accretion rate. Medd is the critical (Eddington) rate above which radiation pressure drives material out. After Nomoto and Kondo (1991). Courtesy Ken-ichi Nomoto.

Matsuo S, Kondo T, Juodkazis S, Mizeikis V, Misawa H (2002) Fabrication of three-dimensional photonic crystals by femtosecond laser interference. In Adibi A, Scherer A, Lin S-Y (eds) Photonic bandgap materials and devices. SPIE Proc 4655 327-334... 

In addition, there are certain metals involving 4f- or 5f-states, formerly called Kondo metals and now described as heavy-fermion materials, which have a very large electronic specific heat and may be described as crystals in which every rare-earth metal is envisaged, coherently, in a Kondo-type spin flip. 

Basler EA, Dadang S, Kondo K, Tanito M (2004) JP 2004201590 A2 20040722 Microbial cellulose gels, their manufacture, and use for food materials... 

The transfer of spectral weight from low frequencies to high frequencies that accompanies the formation of pseudogap matter is the inverse of process in heavy electron materials by which at some onset temperature the itinerant coherent heavy electron state emerges out of the local moments that make up the Kondo lattice. It has recently proved possible to develop a two-fluid description that describes this emergent... 

Shoji, I., Kondo T. A. and Ito R., Second-order nonlinear susceptibilities of various dielectric and semiconductor materials. Opt.Quantum Electr. (2002) 34 797-833. 

Tu. In our study of these materials we have found some evidence that this temperature could be related to a spin flip scattering mechanism which is also responsible for the Kondo resistivity observed in these materials. 

Onodera S, Kondo H, Kawana T (1996) Materials for magnetie-tape media. Mater Res Soc Bull, September 1996 35-41... 

CeCu6 and CeRu2Si2 show neither superconductivity nor magnetic order down to 20 mK. Therefore, the behaviour of 1/7) in these compounds presents a fundamental property of heavy fermion material. As seen in Fig. 3,11,12 1/7) is temperature independent above the Kondo temperature, / , corresponding to a localized state of the 4/ electron. At higher temperatures 1/7) is expected to decrease due to the increase in the fluctuation rate of the localized 4f spin. Below 7k, 1/7) shows a 7) T= constant behaviour corresponding to the Fermi liquid state. 

Kondo, Y., and Wei, R. P., Approach On Quantitative Evaluation of Corrosion Fatigue Crack Initiation Condition, in International Conference on Evaluation of Materials Performance in Severe Environments, EVALMAT 89, Vol. 1, Kobe, Japan, November 20-23... 

Unlike the Kondo systems, a qualitatively different behaviour was observed in the Ce and Yb mixed-valence materials. A stronger coupling between the 4f moments and the conduction-band states is manifest in the much faster relaxation rates and the values of residual IT are about one order of magnitude higher. The striking contrast is underlined by the nearly temperature independent values of T. 

An alternative approach to accounting for the maxima in the temperature dependence of p is based on the Kondo-lattice model (Lavagna et al. 1982). The periodic array of independent Kondo impurities, described by the single-ion Kondo temperature TK, provides a proper description at elevated temperatures, while a coherent state yielding a drop of the resistivity is attained when the system is cooled to below another characteristic temperature coh- Although this approach is suitable particularly for Ce compounds where the Kondo regime was identified inequiv-ocally, the coherence effects are probably significant also in narrow-band actinide materials, as indicated by an extreme sensitivity of the lower-temperature decrease of the resistivity to the presence of impurities. 

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