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Magnetic transitions in metallic compounds determined by RKKY interactions

E. BIRSAN1,* , C. CANDIN2, M. RACUCIU1

Affiliation

  1. Physics Department, University Lucian Blaga, str. Dr I.Ratiu, No.5-7, 550024, Sibiu, Romania
  2. Faculty of Engineering “Hermann Oberth”, University Lucian Blaga of Sibiu, Romania

Abstract

We study the role of RKKY (Ruderman-Kittel-Kasuya-Yosida) interactions in magnetic transitions observed in various metallic compounds. These transitions were found to play an important role in problems involving the interaction of localized moments in a metal, via polarization of conduction electrons. We show the existence of the antiferromagnetismferromagnetism transition in metallic compounds generated by RKKY interactions. We study the role of interstitials impurities in this process and we provide the influence of exchange coupling constant. Indirect exchange couples moments over relatively large distances. It is the dominant exchange interaction in metals where there is little or no direct overlap between neighboring magnetic electrons. It therefore acts through an intermediary, which in metals are the conduction electrons (itinerant electrons). The RKKY exchange coefficient oscillates from positive to negative as the separation of the ions changes and has the damped oscillatory nature. Therefore, depending upon the separation between a pair of ions their magnetic coupling can be ferromagnetic or antiferromagnetic. A magnetic ion induces a spin polarization in the conduction electrons. This spin polarization in the itinerant electron system is felt by the moments of other magnetic ions within range, leading to an indirect coupling..

Keywords

Itinerant ferromagnetism, RKKY interactions, Magnetic transitions.

Submitted at: Nov. 2, 2006
Accepted at: April 15, 2007

Citation

E. BIRSAN, C. CANDIN, M. RACUCIU, Magnetic transitions in metallic compounds determined by RKKY interactions, Journal of Optoelectronics and Advanced Materials Vol. 9, Iss. 4, pp. 911-915 (2007)