Volume 79, Number 5, September 2007
Article Number 57006
Number of page(s) 6
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
Published online 01 August 2007
EPL, 79 (2007) 57006
DOI: 10.1209/0295-5075/79/57006

Coexistence of ferromagnetism and Kondo effect in the underscreened Kondo lattice

N. B. Perkins1, 2, J. R. Iglesias3, M. D. Núñez-Regueiro4 and B. Coqblin4

1  Institute fur Theoretische Physik, TU Braunschweig - Mendelssohnstrasse 3, 38106 Braunschweig, Germany
2  Bogoliubov Laboratory of Theoretical Physics, JINR - Dubna, Russia
3  Instituto de Física, Universidade Federal do Rio Grande do Sul - 91501-970 Porto Alegre, Brazil
4  Laboratoire de Physique des Solides, UMR 8502 CNRS, Université Paris-Sud - 91405 Orsay, France

received 26 January 2007; accepted in final form 10 July 2007; published September 2007
published online 1 August 2007

The coexistence of ferromagnetic order and Kondo behavior, that has been experimentally observed in some uranium compounds, is studied in the framework of an underscreened Kondo lattice model within the mean-field approach. For small values of JK compared to the bandwidth, a ferromagnetically ordered solution is obtained, while for larger values of JK a Kondo regime occurs with a Kondo temperature larger than the Curie temperature, suggesting a scenario for the coexistence of Kondo effect and ferromagnetic order.

71.27.+a - Strongly correlated electron systems; heavy fermions.
75.30.Mb - Valence fluctuation, Kondo lattice, and heavy-fermion phenomena.
75.20.Hr - Local moment in compounds and alloys; Kondo effect, valence fluctuations, heavy fermions.

© Europhysics Letters Association 2007