日本原子力研究開発機構 (JAEA) / 量子ビーム応用研究部門
放射光科学研究ユニット / 放射光量子シミュレーショングループ
|Date and time:||26th Oct. (Thu.) 16:30〜|
|Place:||Lecture room 732, Faculty of Science, University of Hyogo|
|講演タイトル||Extended Dynamical Mean-Field Approximation: Application to Hubbard Model|
|Speaker:||Dr. Hiroaki Kusunose (Tohoku University)|
Dynamics of strongly correlated electron systems has been investigated extensively in context of low-temperature physics in the heavy fermion compounds, the transition metals and some organic materials.A specific feature of such systems is a dual nature of electronic states in one-particle density of states, in which, the high-energy incoherent states (so-called the Hubbard bands) have a spatially localized character, while the low-energy states exhibit an itinerant character with strong temperature dependence. The interplay between the electronic states in two opposite extremes is a vital clue to understand magnetism and superconductivity realized in heavy-fermion systems. It is this aspect however that has hampered many theoretical attempts based on the one extreme, such as weak-coupling approaches or the dynamical mean-field approximation.
I propose a hybrid approach, which takes account of the correction of the spatial fluctuations to the local self-energy obtained by the dynamical mean-field approximation . Using the formalism, it is demonstrated that the one-particle spectral intensity in the two-dimensional Hubbard model at half-filling exhibits the pseudo-gap behavior in the central coherent quasiparticle peak due to the critical antiferromagnetic fluctuation.The specific heat is considerably enhanced by the short-range order, which assists a tendency of the Mott localization showing the reduction of the double occupancy. I will discuss possible future applications with the present formalism, including an anisotropic superconductivity.
 H. Kusunose: J. Phys. Soc. Jpn. 75 (2006) 054713.