A mean-field approach to Kondo-attractive-Hubbard model. (4th January 2018)

• Record Type: Journal Article
• Authors: Costa, Natanael C; de Lima, José P; Paiva, Thereza; El Massalami, Mohammed; dos Santos, Raimundo R
• Is Part Of: Journal of physics. Volume 30:Number 4(2018)
• Publication Date: 2018-01-04
• Subjects: Kondo lattice -- Hubbard model -- superconductivity -- magnetism; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/1361-648X/aaa1ab
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: With the purpose of investigating coexistence between magnetic order and superconductivity, we consider a model in which conduction electrons interact with each other, via an attractive Hubbard on-site coupling U, and with local moments on every site, via a Kondo-like coupling, J . The model is solved on a simple cubic lattice through a Hartree–Fock approximation, within a 'semi-classical' framework which allows spiral magnetic modes to be stabilized. For a fixed electronic density, n c, the small J region of the ground state ( T = 0) phase diagram displays spiral antiferromagnetic (SAFM) states for small U . Upon increasing U, a state with coexistence between superconductivity (SC) and SAFM sets in; further increase in U turns the spiral mode into a Néel antiferromagnet. The large J region is a (singlet) Kondo phase. At finite temperatures, and in the region of coexistence, thermal fluctuations suppress the different ordered phases in succession: the SAFM phase at lower temperatures and SC at higher temperatures; also, reentrant behaviour is found to be induced by temperature. Our results provide a qualitative description of the competition between local moment magnetism and superconductivity in the borocarbides family.