Pentagon chain in external fields

Abstract

We consider a pentagon chain described by a Hubbard type of model considered under periodic boundary conditions. The system (i) is placed in an external magnetic field perpendicular to the plane of the cells, and (ii) is in a site-selective manner under the action of an external electric potential. In these conditions, we show in an exact manner that the physical properties of the system can be qualitatively changed. The changes cause first strong modifications of the band structure of the system created by the one-particle part of the Hamiltonian, and second, produce marked changes of the phase diagram. We exemplify this by deducing ferromagnetic ground states in the presence of external fields in two different domains of the parameter space.

Keywords:

• conducting polymers
• correlated systems
• ferromagnetism
• Hubbard model
• theoretical
• exact results
• non-integrable systems

Notes

No potential conflict of interest was reported by the authors.

1 These conditions represent requirements which provide lower dispersionless band created by external fields.

Additional information

Funding

This work was supported by the Alexander von Humboldt Foundation, Hungarian Research Funds for Basic Research [OTKA K-100288], and the contract [TAMOP 4.2.2/A-11/1/KONV-2012-0036] (co-financed by EU and European Social Fund).