Orbital magnetic moments in pure and doped carbon nanotubes

Abstract

The unusual band structure of carbon nanotubes (CNs) results in their remarkable magnetic properties. The application of magnetic field parallel to the tube axis can change the conducting properties of the CN from metallic to semiconducting and vice versa. Apart from that B induces (via the Bohm-Aharonov effect) orbital magnetic moments µ orb in the nanotube. These moments are studied both in pure and hole-or electron-doped CNs, isolated or in a circuit. Remarkably, µ orb in pure CNs depends uniquely on their original conducting properties, length, and temperature but it does not depend on the nanotube radius or the particular chirality. In doped nanotubes the magnetic moments can be strongly altered and depend on the radius and chirality. Temperature can even change their character from diamagnetic at low T to paramagnetic at high T . A full electron-hole symmetry in doped tubes is also revealed.

Electronic Structure Calculations on Helical Conducting Polymers

“…Several studies proposing molecular solenoids can be found in recent literature. The most studied targets are carbon nanotubes (CNTs), − for which quantum treatments of their magnetic properties have been published. ,− Margańska and co-workers report that application of a magnetic field parallel to the tube axis can change the conducting properties of the CNT from metallic to semiconducting and vice versa. It has been shown that loop currents for small molecules placed between the tip of a scanning tunneling microscope and the substrate can be largely amplified if the energy of the injected electrons is resonant with degenerate eigenstates of the isolated molecule, , a statement that Tsuji et al proposed to be equally applicable to CNTs.…”

Theoretical simulations of magnetic nanotubes using Monte Carlo method

“…One of the potentially interesting aspects of nanophysics is related to magnetic phenomena. In particular, experimental and theoretical investigations of the magnetism in nanostructures stimulates extensive theoretical studies of different materials at the nanometric scale, such as pure and doped different carbon-based materials [6][7][8][9][10][11][12] and semiconductor nanoclusters, ferromagnetic and anti-ferromagnetic nanocrystals [13][14][15][16] and thin films [17]. The new experimental works which have been done recently in this area opened the way for the creation of nanotubes based on the composite molecules that contain metal atoms [18][19][20].…”

“…In particular, different types of theoretical techniques have been used for the numerical simulations of magnetic properties such as the spin model with dipolar and nearest-neighbor interactions [17,21,22], the nearest-neighbor tight-binding Hamiltonian [11,[23][24][25], the calculations using the ab initio pack with the spin-polarized density functional theory [26] and the Monte Carlo simulations [27].…”

Evaluation of physicochemical and mechanical properties with the in vitro degradation of PCL/nHA/MWCNT composite scaffolds

“…The magnetic moment depends on the diameter of the nanotube and it is easier to maintain the chirality the larger the diameter and the temperature. 18 The importance of the magnetic properties of the scaffolds is that they can guide the proliferation, differentiation and mineralization of bone cells. 19…”