Antiferromagnetic metal to heavy-fermion metal quantum phase transition in the Kondo lattice model: A strong coupling approach

摘要

We study the quantum phase transition from an antiferromagnetic metal to aheavy fermion metal in the Kondo lattice model. Based on the strong couplingapproach we {\it first} diagonalize the Kondo coupling term. Since this strongcoupling approach makes the resulting Kondo term {\it relevant}, the Kondohybridization persists even in the antiferromagnetic metal, indicating thatfluctuations of Kondo singlets are not critical in the phase transition. Wefind that the quantum transition in our strong coupling approach results from{\it softening of antiferromagnetic spin fluctuations of localized spins},driven by the Kondo interaction. Thus, the volume change of Fermi surfacebecomes continuous across the transition. ......