X-boson cumulant approach to the topological Kondo insulators

27th International Conference on Low Temperature Physics

Ramos, E.^1 ; Franco, R.^1 ; Silva-Valencia, J.^1 ; Foglio, M.E.^2 ; Figueira, M.S.^3

Departamento de Física, Universidad Nacional de Colombia, Bogotá

A. A. 5997, Colombia^1

Instituto de Física gleb Wataghin, Universidade Estadual de Campinas, Campinas, São Paulo

13083-970, Brazil^2

Instituto de Física, Universidade Federal Fluminense, Niterói, RJ

24210-340, Brazil^3

关键词: Cumulants;    First order transitions;    Kondo insulators;    Periodic Anderson model;    Slave bosons;    Spin-orbit couplings;    Square lattices;    Two-dimension;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/568/5/052007/pdf
DOI  :  10.1088/1742-6596/568/5/052007

来源: IOP

【 摘 要 】

In this work we present a generalization of our previous work of the X-boson approach to the periodic Anderson model (PAM), adequate to study a novel class of intermetallic 4f and 5f orbitals materials: the topological Kondo insulators, whose paradigmatic material is the compound SmB6. For simplicity, we consider a version of the PAM on a 2D square lattice, adequate to describe Ce-based compounds in two dimensions. The starting point of the model is the 4f - Ce ions orbitals, with J 5/2 multiplet, in the presence of spin-orbit coupling. Our technique works well for all of the parameters of the model and avoids the unwanted phase transitions of the slave boson mean field theory. We present a critical comparison of our results with those of the usual slave boson method, that has been intensively used to describe this class of materials. We also obtain a new valence first order transition which we attribute to the dependence of the hybridization.