Актуальные проблемы физики конденсированных сред

Static magnetic susceptibility of the systems with anisotropic Kondo interaction data. However, the comparison with experiment showed that the Curie constant and Weisstemperature considerably differed for low and high temperature regions which may indicate theKondo effect in the static susceptibility data. An importance of Kondo renormalization for spinkinetics suggests it to have an influence on the static properties as well. I n this research weextend the earlier analysis of the static magnetic susceptibility taking into account its possiblerenormalization due to the Kondo effect.2. B a s i c m o d e lWe start from the local properties of an Yb-ion in the tetragonal CEF. A free Y b3 +- i o n has a 4f1 3 configuration with one term2F . The spin orbital interaction splits the2F term into twomultiplets:2F7/2 with J = 7/2 and2F5/2 with J = 5/2, where J denotes the value of the totalmomentum J = L + S with L and S as the orbital and spin momentum of the ion. The excitedmultiplet2F5/2 is separated from the ground state2F7/2 by about 1 eV. Since this value is muchlarger than the CEF energy, we consider in the following the ground multiplet only. Within thelowest multiplet the spin and orbital momentums of the ion are expressed via its total electronicmomentum and the Lande g-factor gj: S = (gj — 1)3, L = (2 — gj)3. I n this way the Zeemanenergy of Yb-ions can be written as followstfZJ = — H M j , (1)where H denotes the external magnetic field and M j is the total magnetic moment of Yb-ions.M j = -VBQJY^Ji- (2)гThe Kondo exchange coupling of the Yb-ion with conduction electrons and the indirect inter-action between Yb-ions via the conduction electrons ( R K K Y interaction) are also expressed interms of the total momentum J:Hja = A0(gj -1)^2 СГгЗг, (3)г# R K K Y = (gj - I)2 ^2 ^RKKYJ»JJ > (4)Here Ao denotes the zero order term of the Kondo exchange integral expansion in multipoles(details can be found in [20-25]), cr^ is the spin density...