Search results for "electromigration"
showing 9 items of 19 documents
Domain wall pinning in ultra-narrow electromigrated break junctions
2014
The study of magnetic domain walls in constrained geometries is an important topic, yet when dealing with extreme nanoscale magnetic systems artefacts can often dominate the measurements and obscure the effects of intrinsic magnetic origin. In this work we study the evolution of domain wall depinning in electromigrated ferromagnetic junctions which are both initially fabricated and subsequently tailored in-situ in clean ultra-high vacuum conditions. Carefully designed Ni(80)Fe(20) (Permalloy) notched half-ring structures are fabricated and investigated as a function of constriction width by tailoring the size of the contact using controlled in-situ electromigration. It is found that the dom…
Domain-wall induced large magnetoresistance effects at zero applied field in ballistic nanocontacts
2013
We determine magnetoresistance effects in stable and clean Permalloy nanocontacts of variable cross section, fabricated by UHV deposition and in situ electromigration. To ascertain the magnetoresistance (MR) effects originating from a magnetic domain wall, we measure the resistance values with and without such a wall at zero applied field. In the ballistic transport regime, the MR ratio reaches up to 50% and exhibits a previously unobserved sign change. Our results can be reproduced by recent atomistic calculations for different atomic configurations of the nanocontact, highlighting the importance of the detailed atomic arrangement for the MR effect. DOI: 10.1103/PhysRevLett.110.067203
Scaling of intrinsic domain wall magneto-resistance with confinement in electromigrated nanocontacts
2018
In this work we study the evolution of intrinsic domain wall magnetoresistance (DWMR) with domain wall confinement. Clean permalloy notched half-ring nanocontacts are fabricated using a special ultra-high vacuum electromigration procedure to tailor the size of the wire in-situ and through the resulting domain wall confinement we tailor the domain wall width from a few tens of nm down to a few nm. Through measurements of the dependence of the resistance with respect to the applied field direction we extract the contribution of a single domain wall to the MR of the device, as a function of the domain wall width in the confining potential at the notch. In this size range, an intrinsic positive…
Nonlinear photon-assisted tunneling transport in optical gap antennas.
2014
International audience; We introduce strongly coupled optical gap antennas to interface optical radiation with current-carrying electrons at the nanoscale. The transducer relies on the nonlinear optical and electrical properties of an optical gap antenna operating in the tunneling regime. We discuss the underlying physical mechanisms controlling the conversion involving d-band electrons and demonstrate that a simple two-wire optical antenna can provide advanced optoelectronic functionalities beyond tailoring the electromagnetic response of a single emitter. Interfacing an electronic command layer with a nanoscale optical device may thus be facilitated by the optical rectennas discussed here.
Effect of quantized conductivity on the anomalous photon emission radiated from atomic-size point contacts
2019
We observe anomalous visible to near-infrared electromagnetic radiation emitted from electrically driven atomic-size point contacts. We show that the number of photons released strongly depends on the quantized conductance steps of the contact. Counter-intuitively, the light intensity features an exponential decay dependence with the injected electrical power. We propose an analytical model for the light emission considering an out-of-equilibrium electron distribution. We treat photon emission as bremsstrahlung process resulting from hot electrons colliding with the metal boundary and a find qualitative accord with the experimental data.
Influence of crystal defects on the electromigration of the hydrogen in palladium
2001
Abstract Electromigration and diffusion of hydrogen in palladium defected through quenching to liquid nitrogen temperature were investigated. It was found that the obtained experimental results cannot be described by means of a single flux of hydrogen which diffuses in a gradient of electric field. In order to effectively explain the obtained results, a theoretical model was elaborated. It assumed the existence of the following two fluxes of hydrogen in the quenched metal: • Ji—of migration, according to the interstitial mechanism, and • Ji–d—of migration, according to the interstitial-defective mechanism. Dependence of effective valences and diffusion coefficients for both mechanisms of tr…
Physical Methods for Enhancing Oral Mucosal Delivery: Sonophoresis, Iontophoresis and Electroporation
2015
The need for more rapid onset of action and improved absorption of medications has resulted in great development of drug delivery technologies. Transmucosal drug delivery offers a convenient route of administration for a variety of clinical indications. Unfortunately, the wide variability in structure of the oral mucosal tissues could constitute a key factor in drug penetration and absorption. To circumvent this obstacle and to increase the drug flux through the mucosal membranes, different approaches to permeation enhancement are used. This chapter describes the most significant aspects of the physical techniques widely used such as sonophoresis, iontophoresis, and electroporation. These p…
Investigation of diffusion and electromigration of hydrogen in palladium and PdAg alloy
1999
Abstract Diffusion and electromigration of hydrogen in PdH 0.1 , Pd 77 Ag 23 H 0.1 and Pd 50 Ag 50 H 0.1 alloy were measured by means of resistivity method. It is known that hydrogen migrates towards the cathode within the temperature range of 300–473 K in the PdH 0.1 and Pd 77 Ag 23 H 0.1 system. In Pd 50 Ag 50 H 0.1 , hydrogen migrates towards the cathode below 400 K, but towards the anode at higher temperatures. Its effective valency increases together with temperature. At the same time it satisfies the linear dependence on inverse specific resistance ρ : Z eff = Z i +( k / ρ ). The constants Z i and k have the following values: (1.05±0.01) and −(3.81±0.04)×10 −8 Ω m for hydrogen in PdH …
Rectifications optique et thermique générées à l'aide de jonctions tunnel planaires électromigrées
2017
The work described in this manuscrit consists in studying the optical rectification within plasmo-electronic devices. These ultra-compact optically adressed components with an ultra-fast time response induces a conversion of the incident field into a static current. The monolithically-integrated electronically optical antenna requires a detailed knowledge of nanoscale thermal and electrical transport mechanisms. This work also aims to discuss all thermal effects inherent in the optical excitation of these connected devices, in order to identify the different contributions in the generation of a photo-assisted current.