The de Haas-van Alphen effect in Kondo systems

Abstract

In Kondo systems, de Haas-van Alphen experiments determine a spin-splitting term in the conduction-electron self-energy. It is shown that for all temperatures and magnetic fields, and in the presence of normal potential scattering from the magnetic impurity, spin-splitting of Landau levels is given exactly with Re Sigma spindown(0)-Re Sigma spinup(0)=cJ(Sz)K Sigma sigma (0) is the conduction-electron self energy at the Fermi level and (Sz)K is the expectation value for the impurity spin including Kondo effects. This equation also applies for both the large-U (Kondo) and small-U limits of the Anderson model, with (Sz)K to (Sz)A for the small-U case. (Sz)K,A does not obey the field and temperature dependence of the Brillouin function, but instead follows the Langevin function. This is so because the Friedel-Anderson impurity d orbitals are populated successively by many electrons during the impurity-spin relaxation time.