Influence of local environment on Co magnetic behavior in Y2(Co,M)7B3 compounds, where MÂ =Â Cu or V

The magnetic properties of Y2Co7−xMxB3 compounds, with M = Cu or V, and x ≤ 2, were investigated in the temperature range 4.2-850 K and in magnetic fields of up to 7 T. Electronic structure calculations using the tight binding linear muffin-tin orbitals method in the atomic sphere approximation (TB-LMTO-ASA) were performed for the compounds with x = 1. The variations of the Curie temperatures, spontaneous magnetization and of the mean Co moment at 4.2 K are discussed in correlation with the structural characteristics, site localization of the M atoms and dilution effects. The Co behavior is described in the general theory of spin fluctuations.