Heavy Fermion — Kondo Lattice

Kondo Screening & Heavy Bands

Heavy fermion compounds (e.g., CeAl₃, UPt₃, YbRh₂Si₂) contain localized f-electrons that couple antiferromagnetically to conduction electrons via the Kondo interaction J.

Below the Kondo temperature T_K, each f-moment is screened by conduction electrons, forming a singlet. The resulting quasiparticles are extraordinarily heavy: m* ~ 100–1000 m_e.

In a lattice, the hybridization opens a gap near E_F, creating a narrow "Kondo resonance" — a huge peak in the DOS at E_F (Abrikosov-Suhl resonance).

T_K ~ D exp(−1/J·N(E_F))
m*/m ~ 1 + J·N(E_F) ≫ 1
Hybridized bands: E±(k) = ½(ε_k+ε_f) ± ½√((ε_k−ε_f)²+4V²)
DOS peak at E_F: N*(E) ~ 1/T_K

Kondo coupling J 0.3 Hybridization V 0.2 Temperature T/T_K 0.2 f-level ε_f -0.3

Heavy Fermion Metal — Kondo Lattice

Kondo Screening & Heavy Bands