Kondo effect in an antiferromagnetic metal: Renormalization group analysis and a variational calculation

We study the fate of a spin-1/2 impurity in the itinerant antiferromagnetic metallic phase via a renormalization group analysis and a variational calculation. The local moment—conduction electron interaction Hamiltonian in an antiferromagnetic metal is spin nonconserving. We show that for a general location of the impurity, the Kondo singularities still occur, but the ground state has a partially unscreened moment. We calculate the magnitude of this residual moment and the variation of the spin polarization with energy for a substitutional impurity as a function of the staggered magnetization. The usual Kondo effect only occurs if the impurity is placed at points where the magnetization is zero.

Figure 1

(a) Particle-particle channel, (b) Particle-hole channel contributions to the vertex and (c) Contribution to the pseudo-fermion self energy

Figure 2

Density of states for the two bands. For all numerical calculations, except when noted otherwise, the bandwidth is taken to be 10 and $\gamma m=0.05$.

Figure 3

Flow of $v\left(\cdot \cdot \right)$ and $J_z\left(---\right)$ where the initial values are $J_z=-0.4$ and $J_{\perp }=-0.4$. For comparison we also show the flow of $J_{z_0}(-)$ in the absence of AFM order.

Figure 4

(Color online) Binding energy normalized to that in the absence of magnetic order, $E_0\left(\gamma m=0\right)$ and net moment of the collective state for fixed value of the exchange coupling, $J=-0.04$.

Figure 5

(Color online) Local spin-resolved DOS for the impurity located at the “up-spin” site for spins parallel (up) and antiparallel (down) to $m$ where $\gamma m=0.05$ and $J=-0.04$.