Heavy Fermion Systems

f-electron hybridization · Kondo lattice · effective mass enhancement

Hybridization V 0.40
f-level energy εf 0.00
Temperature T/TK 0.20
120
m*/me
0.08
Hybridization Gap
Kondo
Phase
2.4
DOS at EF

About

Heavy fermion materials (e.g., CeCu₆, UBe₁₃, YbRh₂Si₂) contain lanthanide or actinide ions whose localized f-electrons hybridize with itinerant conduction electrons via the Kondo lattice model. Below the Kondo temperature TK, coherent hybridization opens a narrow gap in the conduction band, creating quasiparticles with effective masses m* up to ~1000 mₑ. The competition between Kondo screening (favoring a non-magnetic heavy Fermi liquid) and RKKY exchange (favoring magnetic order) drives rich phase diagrams including unconventional superconductivity, non-Fermi liquid behavior, and quantum critical points.