Interplay of magnetism and screening in the Kondo Lattice

An increasing body of experimental evidence suggests that frustration and the Kondo effect have complimentary roles that act together to either reduce, or completely eliminate magnetic order in heavy electron systems[1]. I will review our attempts to explore the joint effects of frustration and Kondo effect in the Kondo Heisenberg model, using the large N Schwinger boson approach[2]. These results will be discussed in the context of recent doping experiments on YbRh$_2$Si$_2$ [3], where an intermediate spin liquid appears to develop between the antiferromagnet and the large Fermi surface metal. \\ $\hbox{[1]}$ S. Nakatsuji, Y. Machida et al, Phys. Rev. Lett. 96, 087204 (2006).\\ $\hbox{[2]}$ J. Rech, P. Coleman, O. Parcollet and G. Zarand, Phys. Rev. Lett. 96, 016601 (2006).\\ $\hbox{[3]}$ T. Westerkamp, P. Gegenwart, C. Krellner et al., Physica B - Condens. Matter 403, 1236-1238 (2008).