Exploring the conduction in atomic-sized metallic constrictions created by controlled ion etching

Abstract

A novel technique to establish atomic-sized contacts in metallic materials is shown. It is based on etching a (sub)micrometric electrode via a low-energy focused ion beam. The in situ measurements of the nanoconstriction resistance during the etching process permit control of the formation of atomic-sized constrictions with milling time, observing steps in the conductance in the range of the conductance quantum (G(0) = 2e(2)/h), just before entering the tunnelling regime. These constrictions are highly stable with time due to the adherence to a substrate, which allows further studies such as the detailed current-voltage transport investigation reported here. Scanning electron microscopy images are used to correlate the etching process and the constriction microstructure. The high control achieved in the process makes us suggest this technique as a promising route to study physical phenomena in the verge of the metal-tunnel conduction crossover.

Origin of the Difference in the Resistivity of As-Grown Focused-Ion- and Focused-Electron-Beam-Induced Pt Nanodeposits

“…The possibility of in-situ control of the electrical resistance during deposition, which is demonstrated in Figure 3, is very interesting and has been previously reported with different approaches in [12,25]. In our case, by careful initial positioning of the electrical microprobes with respect to the contact electrodes and final adjustments with the help of the electron and ion beams imaging, it is possible to realize in-situ good electrical contacts between the probes and the contact electrodes [22]. Thus, if we locate the electrical microprobes on a metallic electrode, we measure 13 Ω, which is the specified lead resistance.…”

“…Electrical microprobes (from Kleindiek) were used for precise in-situ control of the deposit resistance [22]. These conductive microprobes are connected via a feedthrough to a Keithley 2000 multimeter located out of the dual beam chamber, which allows measuring the deposit resistance by two-probe measurements provided that its value is below 120 MΩ.…”

Tunneling and anisotropic-tunneling magnetoresistance in iron nanoconstrictions fabricated by focused-ion-beam

“…However, the fabrication of constrictions by these techniques in the sub-100 nm range is extremely difficult, and the creation of atomic-size constrictions is especially challenging. We recently demonstrated a new way to fabricate stable atomic-size constrictions, by the control of the resistance while the FIB etching is performed [14,15]. In this work we show the first magnetoresistance results in one iron nanoconstriction obtained by this method.…”

The influence of Ga+irradiation on the transport properties of mesoscopic conducting thin films

“…This FIB technique has been successfully used for nanostructuring different materials like magnetic and superconducting [2,3,4] or more recently to study the conduction behavior in metallic constrictions [5]. One of the advantages of this technique is its versatility; the use of any resist appears, a priory, unnecessary.…”