Magnetoresistance of an entangled single-wall carbon-nanotube network

Abstract

The resistivity (T) and magnetoresistance ͑MR͒ (⌬/) of an entangled single-wall carbon-nanotube network are investigated. The temperature dependence of the resistivity shows a negative d/dT from T ϭ4.3-300 K with no resistivity minimum, which is fitted well to the two-dimensional variable-range-hopping ͑VRH͒ "(T)ϭ 0 exp͓(T 0 /T) 1/3 ͔… formula with T 0 ϭ259.2 K. The MR shows a negative H 2 behavior at low magnetic field. At Tр3.8 K and high magnetic field, the negative MR becomes positive. The positive MR tends to be saturated for HϾ10 T. The negative MR with a positive upturn can be decomposed into a positive contribution from the two-dimensional spin-dependent VRH and a negative contribution from the twodimensional weak localization, with some contribution of the Ni impurities in the sample found with the transmission electron microscope and by energy dispersive spectrometer analysis. ͓S0163-1829͑98͒07848-5͔

Encapsulation of single-molecule magnets in carbon nanotubes

“…Both samples Mn 12 Ac@GMWNT (1) and GMWNT (3) exhibited high roomtemperature-specific conductivities of ca. 20 S cm − 1 , which decrease with temperature (Supplementary Figs S20 and S21) due to intertube contact resistance 30,31 . This indicates that the nanotubes filled with SMM molecules retain their intrinsic electric properties.…”

A role of phonon-assisted tunnelling in electrical conductivity of carbon nanotube networks

“…The current-voltage dependences, measured at various temperatures for a rope of semiconducting SWCNT by Moriyama et al [22] and fitted to the theoretical W (E, T ) dependences using equation (3), are shown in Fig. 1(a, b).…”

“…Kaiser et al [2] pointed out similarity between the resistivity versus temperature behaviour ρ(T ) observed in SWCNT and that of highly conducting polymers, in particular the change of the ρ(T ) dependence from metallic to non-metallic as the temperature was decreased. In analogy to the conducting polymers, the authors of [2,3] have described this resistivity behaviour by a model of metallic conduction in aligned nanotubes with hopping or tunnelling through small electrical barriers corresponding to defects of various types.…”

“…The existing interpretations of this problem can be classified into two categories: the variable range hopping (VRH) [3][4][5][6] or the weak localization (WL), which emphasizes the role of the junctions as energy barriers between metallic regions [2,[7][8][9][10]. According to the VRH mechanism, the dependence ρ(T ) is described by the formula…”

Carbon Nanotube Based Magnetic Tunnel Junctions (MTJs) for Spintronics Application

“…Spintronics devices exploiting the spin of the electron [1][2][3][4][5][6][7][8][9][10] are prepared to revolutionise the electronics industry. The significance of this new generation device is faster memory and lower power consumption at low electron density.…”