Kondo insulators

✍ Scribed by Z Fisk; J.L Sarrao; S.L Cooper; P Nyhus; G.S Boebinger; A Passner; P.C Canfield

• Book ID: 103942543
• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 347 KB
• Volume: 223-224
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/0921-4526(96)00136-6

✦ Synopsis

We discuss Kondo insulators in the context of recent experimental results. These experiments address the questions of the relationship of spin and charge excitations, the temperature dependence of the gap, and the existence of 'failed' insulators.

The small class of f-element compounds known as Kondo insulators are all in a certain sense 'valence' compounds: the f-elements that are present in these compounds have unstable valence, with the valence corresponding to the non-magnetic f-state of the element satisfying the valence requirements of the other elements in the material. A few cases require special consideration, but it is also the case that semiconducting analogs exist for these materials, with the f-element replaced by an isovalent element. The problem can be viewed as a very simple limiting case of the correlated electron, l~tttice: exactly one half-filled band interacting with one occupied f-level. This also corresponds to a simple limiting case of the Kondo lattice with one conduction electron to screen one moment at each site.