Spin-dependent Mass Enhancement under a Magnetic Field in the Periodic Anderson Model(Condensed matter: electronic structure and electrical, magnetic, and optical properties)

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In order to study the mechanism underlying the mass enhancement in heavy-fermion compounds in the presence of a magnetic field, we study the periodic Anderson model by using the fluctuation exchange approximation. The resulting mass enhancement factor can have a value up to 10, which is significantly larger than that in the single-band Hubbard model. We show that the difference between the magnitude of the mass enhancement factor of up-spin (minority spin) electrons z^<-1>_↑ and that of down-spin (majority spin) electrons z^<-1>_↓ increases with the applied magnetic field B ‖ z, which is consistent with the de Haasvan Alphen measurements for CeCoIn_5, CeRu_2Si_2, and CePd_2Si_2. We predict that z^<-1>_↑>z^<-1>_↓ in many Ce compounds, whereas z^<-1>_↑<z^<-1>_↓ in Yb compounds.
社団法人日本物理学会の論文
2008-02-15