Ferromagnetic semiconductor single wall carbon nanotube

TL;DR

This paper explores the potential for ferromagnetic semiconducting behavior in doped single wall carbon nanotubes, revealing phase transitions between semiconductor and metallic states influenced by impurity concentration and coupling strength.

Contribution

It introduces a model for ferromagnetism in doped SWCNTs and analyzes how impurity parameters affect electronic phase transitions.

Findings

Low impurity concentration maintains semiconducting spin up electrons.

Increasing impurity concentration closes the semiconducting gap, inducing a phase transition.

Strong coupling preserves semiconducting spin up electrons while spin down become metallic.

Abstract

Possibility of a ferromagnetic semiconductor single wall carbon nanotube (SWCNT), where ferromagnetism is due to coupling between doped magnetic impurity on a zigzag SWCNT and electrons spin, is investigate. We found, in the weak impurity-spin couplings, at low impurity concentrations the spin up electrons density of states remain semiconductor while the spin down electrons density of states shows a metallic behavior. By increasing impurity concentrations the semiconducting gap of spin up electrons in the density of states is closed, hence a semiconductor to metallic phase transition is take place. In contrast, for the case of strong coupling, spin up electrons density of states remain semiconductor and spin down electron has metallic behavior. Also by increasing impurity spin magnitude, the semiconducting gap of spin up electrons is increased.