Quantitative magnetic force microscopy on permalloy dots using an iron filled carbon nanotube probe.

An iron filled carbon nanotube (FeCNT), a 10-40 nm ferromagnetic nanowire enclosed in a protective carbon tube, is an attractive candidate for a magnetic force microscopy (MFM) probe as it provides a mechanically and chemically robust, nanoscale probe. We demonstrate the probe's capabilities with images of the magnetic field gradients close to the surface of a Py dot in both the multi-domain and vortex states. We show the FeCNT probe is accurately described by a single magnetic monopole located at its tip. Its effective magnetic charge is determined by the diameter of the iron wire and its saturation magnetization 4πM(s) ≈ 2.2 × 10(4)G. A magnetic monopole probe is advantageous as it enables quantitative measurements of the magnetic field gradient close to the sample surface. The lateral resolution is defined by the diameter of the iron wire and the probe-sample separation.

Robust determination of Young's modulus of individual carbon nanotubes by quasi-static interaction with Lorentz forces.

Young's modulus of an individual multi-wall carbon nanotube has been determined by the method of quasi-static transverse bending due to a Lorentz force observed in situ in a transmission electron microscope. The deflection of the nanotube allows the determination of Young's modulus using Euler-Bernoulli's beam equation. Because we determine the specific dependence of the deflection on the position along the nanotube axis, it is possible to gain insight into the type of mountings and furthermore allows for an estimation of the homogeneity of the nanotube. Both properties have been found to be of importance to determine Young's modulus. It was found to be higher by up to a factor of 1.6 compared to the value obtained by assuming rigid mountings.

Iron filled carbon nanotubes as novel monopole-like sensors for quantitative magnetic force microscopy.

We present a novel ultrahigh stability sensor for quantitative magnetic force microscopy (MFM) based on an iron filled carbon nanotube. In contrast to the complex magnetic structure of conventional MFM probes, this sensor constitutes a nanomagnet with defined properties. The long iron nanowire can be regarded as an extended dipole of which only the monopole close to the sample surface is involved in the imaging process. We demonstrate its potential for high resolution imaging. Moreover, we present an easy routine to determine its monopole moment and prove that this calibration, unlike other approaches, is universally applicable. For the first time this enables straightforward quantitative MFM measurements.

Preparation of CNT-copper matrix composite films.

Copper matrix composite thin films reinforced with multiwall carbon nanotubes (CNT-Cu-MC) have been processed by electroplating on conducting or insulating underlayers on oxidized (100)Si substrates using iron catalyst particles. The nanotubes were grown by thermal or plasma enhanced catalytic CVD process. Enhanced interfacial strength to copper was achieved after covering the CNTs by plasma enhanced atomic layer deposition (PEALD) of a thin Ta-N or Ta-N/Zr-O interlayer. For copper plating a conventional copper electrolyte with additives (Ethone) was applied. The density of CNTs and their growth determine primarily the quality of the composite films. A sufficient dispersion of CNTs in the copper matrix and homogeneous copper plating were obtained for low density of CNTs. The CNT reinforcement changes the microstructure and electrical properties of electroplated copper films. The resistivity of the Cu films increases by multiwall CNT reinforcement as a result of changed microstructure.