Chiral currents in gold nanotubes

Abstract

Results are presented for the electron current in gold chiral nanotubes (AuNTs). Starting from the band structure of (4, 3) and (5, 3) AuNTs, we find that the magnitude of the chiral currents are greater than those found in carbon nanotubes. We also calculate the associated magnetic flux inside the tubes and find this to be higher than the case of carbon nanotubes. Although (4,3) and (5,3) AuNTs carry transverse momenta of similar magnitudes, the low-bias magnetic flux carried by the former is far greater than that carried by the latter. This arises because the low-bias longitudinal current carried by a (4,3) AuNT is significantly smaller than that of a (5,3) AuNT.PACS numbers: 73.63. Nm, 73.63.Fg, 73.22.D Nanotubes and nanowires are of interest, not only because of their potential for deployment as interconnects, p-n junctions and rectifiers [1,2] in future nanoscale circuits, but also because they exhibit fundamental physical properties, such as conductance quantisation [3,4], and magic numbers reflecting structural stabilities [5,6]. One ubiquitous property associated with nanotubes is chirality, which arises because there is an infinite number of ways of rolling up a two-dimensional periodic lattice to form a cylinder. In addition to widely-studied carbon nanotubes [7], chiral nanotubes have been formed from a range of other materials, including gold [5,8,9], platinum [10], silver [11], alkaline metals [12][13][14] and boron nitride [15,16]. These experimental observations have been supported by a range of theoretical investigations [17][18][19][20][21][22].It has recently been noted that the presence of intrinsic chiral electron currents in chiral nanotubes can be exploited to yield photogalvanic effects in heteropolar nanotubes [17], a new drive mechanism in carbon-nanotube windmills [23] and to produce internal magnetic fields in carbon nanotube solenoids [24] . In each of these examples, the underlying lattice is hexagonal, with two atoms per unit cell. In contrast nanotubes formed from gold, silver and platinum are derived from triangular lattices with one atom per unit cell and therefore it is of interest examine whether or not these effects are enhanced or diminished compared with their carbon counterparts.In this paper, to answer these questions, we examine chiral currents in gold nanotubes. Our choice of gold is in part motivated by the fact that chiral currents are expected to scale with the Fermi velocity of the underlying two-dimensional lattice, which in gold is approximately double that of graphene.A nanotube formed from a 2D lattice with periodic boundary conditions can be described by a chiral vector C = na 1 + ma 2 , which defines the circumference of the nanotube, where a 1 , a 2 are the lattice vectors and n, m are integers. The axis of the nanotube lies parallel to the longitudinal translation vector T (which is perpendicular the the chiral vector), whose magnitude is equal to the length of the nanotube unit cell, along the tube axis. To understand the currents carried by such a nanotu...

Vibrational properties of single-walled silver nanotubes studied from first principles

“…Another ab initio density functional theory calculations give further evidence that the hollow (4,4) SWSNT is structurally intrinsic and not caused by the contamination of light atoms (H, C, N and O) [7]. The experimental observations of the single-walled gold and silver tubes have also stimulated greatly the researcher's interests in them, both experimentally and theoretically, [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] due to their unique physical and chemical properties, and also potential applications in future nanoelectronics and nano-optics, hydrogen storage, catalysis.…”

Charge transport behavior of 1D gold chiral nanojunctions

“…Recent years have seen a sizeable amount of study on one-dimensional (1D) nanostructures in the form of nanotubes (NTs) and nanowires (NWs), primarily because of their potential applications in nanodevice technology [1,2,3,4,5,6,7,8,9,10]. Among these, chiral nanostructures continue to garner interest due especially to their characteristic helicity that often displays the ability to control the physical properties in somewhat more flexible way.…”

“…Using a tight-binding spiral model, Yevtushenko et al [9] have demonstrated that electronic transport may get affected considerably by the interplay between chirality and nonlinearity in a chiral CNT. However, the works by Manrique et al [10] reveal that like in CNTs, chiral currents are also oscillatory functions of energy in Au(5,3)NTs, but the magnitude of chiral currents are much larger in the latter. The first experimental observation of chiral Au(5,3)NT based nanobridges was reported…”

“…Our f irst − principles quantum transport analysis further suggests that chiral Au(7,3)NWs render higher electronic conductance than chiral gold (5,3) nanotubes (NTs), once bridged by either σ-saturated or π-conjugated molecular moieties. It, however, turns out that asymmetricity in the characteristics of channel formation at the lead-molecule contact remains often associated with chiral Au(7,3)NWs only.Recent years have seen a sizeable amount of study on one-dimensional (1D) nanostructures in the form of nanotubes (NTs) and nanowires (NWs), primarily because of their potential applications in nanodevice technology [1,2,3,4,5,6,7,8,9,10]. Among these, chiral nanostructures continue to garner interest due especially to their characteristic helicity that often displays the ability to control the physical properties in somewhat more flexible way.…”

Adsorbate and defect effects on electronic and transport properties of gold nanotubes

“…8 Owning to their helical structures, gold nanotubes have unique electronic and catalytic properties. It was predicted by theoretical study that the chiral current flowing through gold tubes may induce strong magnetic field; 9,10 Moreover, both experimental and theoretical investigations have demonstrated excellent catalytic activity of gold nanotubes. 11,12 These unique properties of gold nanotubes suggest promise of gold tubes for future applications of nanoelectronics and nanocatalysis.…”