Revisited Doniach diagram: Influence of short-range antiferromagnetic correlations in the Kondo lattice

Abstract

The Kondo lattice model including nearest-neighbor magnetic exchange interactions is studied here in a mean-field approximation describing both the Kondo state and the intersite magnetic correlations. In the case of antiferromagnetic correlations, our model yields a decrease of the Kondo temperature compared to the one-impurity value, giving, therefore, a ''revisited'' version of the Doniach diagram with a rather flat Kondo temperature in the nonmagnetic case, as observed in several cerium compounds. Our model shows also that short-range magnetic correlations can appear at a temperature clearly larger than the Kondo temperature, as observed in compounds such as CeCu 6 or CeRu 2 Si 2 . ͓S0163-1829͑97͒04642-0͔

Thermal and magnetic properties of the low-temperature antiferromagnetCe4Pt12Sn25

“…11 and 12. There have been a number of theoretical attempts to model such systems using the periodic Anderson model 13 and Kondo lattice model. 14 A mean-field model of the Kondo lattice including the nearest-neighbor magnetic interaction 15 yields a reduction in the Kondo temperature, T K , at J Ͼ J c compared to its value for a single impurity. This result emphasizes the importance of the RKKY coupling even when the system is in the Kondo ͑HF͒ ground state.…”

Theory of the Kondo Lattice: Competition Between Kondo Effect and Magnetic Order

“…We will give here a very brief 3 F o r P e e r R e v i e w O n l y summary of the work presented in ref. [16,17] and obviously details can be found in these papers.…”

“…Then,with this notation we perform an extended mean-field approximation [15,18] which is presented in full detail in Ref. [16,17]. Considering translational invariance and taking into account that there are no magnetic states, we can 4 and the f band of effective band width 2BD, with B given by :…”

“…The reference energy E 0 of the f band and the chemical potential µ have to be determined self-consistently in order to keep the average numbers of f and conduction electrons respectively equal 5 We have previously treated the half-filled case, corresponding to a number of conduction electrons n = 1 [16] and then the general case of a non-integer number of conduction electrons [17]. In this previous paper, we have determined both the temperature T cor for the occurrence of short-range magnetic correlations and the Kondo temperature T K for the lattice, which is different from the one-impurity Kondo temperature T K0 obtained for J H = 0.…”

Antiferromagnetism and spin glass in a Kondo lattice

“…(1)) cannot be considered completely independent from each other [7], we introduce a relationship between J 0 and J K :…”