動的平均場近似によるスピン 1/2 Falicov-Kimball 模型における準周期性と価数揺らぎ

Xiaohui Li, Zewei Chen, Tai Kai Ng

In this paper we extend the Falicov-Kimball model (FKM) to the case where the ``quasiparticles'' entering the FKM are not ``ordinary'' fermions. As an example we first discuss how the FKM can be generalized to the case with spin-dependent hopping. Afterward, we discuss several cases where the quasiparticles entering the FKM are Majorana fermions [extended Majorana-Falicov-Kimball model (MFKM)]. Two examples of the extended MFKM are discussed in detail: (i) a $p$-wave BCS superconductor on a bipartite lattice and (ii) a BCS-Anderson model. We also discuss the most general forms of extended MFKM, including a brief discussion of the case where the Majorana fermions represent spins but not real fermion particles.

譲治 那須, Joji Nasu, 龍 新崎 +3 more

Masahiro Kadosawa, Satoshi Nishimoto, Sugimoto Koudai +1 more

Andrij M. Shvaika, James K. Freericks

Falicov and Kimball proposed a real-axis form for the free energy of the Falicov-Kimball model that was modified for the coherent potential approximation by Plischke. Brandt and Mielsch proposed an imaginary-axis form for the free energy of the dynamical mean field theory solution of the Falicov-Kimball model. It has long been known that these two formulas are numerically equal to each other; an explicit derivation showing this equivalence is presented here.

Samir El Shawish, J. Bonča, Cristian D. Batista

The thermodynamic properties of the extended Falicov-Kimball model (FKM) for spinless fermions are studied as a function of temperature, doping, and interlevel spacing on the two-dimensional lattice. Thermodynamic quantities are calculated using the finite-temperature Lanczos method with additional phase averaging for a system of $4\ifmmode\times\else\texttimes\fi{}4$ sites. Changes of the thermodynamic properties are studied as the system evolves from its symmetric limit represented by the original Hubbard model to the other limiting case, which corresponds to the original FKM for spinless fermions. Our results indicate that valence transition exists in the extended Falicov-Kimball model.

B. Zenker, Dieter Ihle, F. X. Bronold +1 more