Green's function approach to ferromagnetism on the Kondo lattice

✍ Scribed by Ben Hur Bernhard

• Publisher: Elsevier Science
• Year: 2005
• Tongue: English
• Weight: 174 KB
• Volume: 359-361
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/j.physb.2005.01.206

✦ Synopsis

Kondo compounds exhibit a rich phase diagram, which involves different types of magnetic ordering and superconductivity, depending on temperature, pressure and electron concentration. In the Kondo lattice model, we develop the chain of equations of motion generated by the conduction electron Green's function G s ij ðoÞ hhc is ; c y js ii and by spin Green's function w s ij ðoÞ ¼ hhS s i ; S s j ii: The third generation Green's functions are approximated as combinations of the lower-order Green's functions. The method allows the evaluation of the f electron and conduction-electron magnetizations hS z i i and hs z i i and the local spin correlations hS z i s z i i and hS þ i s À i i as self-consistent parameters. We investigate in particular the stability of the ferromagnetic phase on a cubic lattice. The magnetizations and local correlations are calculated as a function of temperature for fixed values of the Kondo exchange J and the conduction electron concentration n.