Multi-state and non-volatile control of graphene conductivity with surface electric fields

Planar electrodes patterned on a ferroelectric substrate are shown to provide lateral control of the conductive state of a two-terminal graphene stripe. A multi-level and on-demand memory control of the graphene resistance state is demonstrated under low sub-coercive electric fields, with a susceptibility exceeding by more than two orders of magnitude those reported in a vertical gating geometry. Our example of reversible and low-power lateral control over 11 memory states in the graphene conductivity illustrates the possibility of multimemory and multifunctional applications, as top and bottom inputs remain accessible.Comment: Graphene ferroelectric lateral structure for multi-state and non-volatile conductivity control, 4 pages, 4 figure

Subcoercive and multilevel ferroelastic remnant states with resistive readout

Ferroelectric devices use their electric polarization ferroic order as the switching and storage physical quantity for memory applications. However, additional built-in physical quantities and memory paradigms are requested for applications. We propose here to take advantage of the multiferroic properties of ferroelectrics, using ferroelasticity to create a remnant strain, persisting after stressing the material by converse piezoelectricity means. While large electric fields are needed to switch the polarization, here writing occurs at subcoercive much lower field values, which can efficiently imprint multiple remnant strain states. A proof-of-principle device, with the simplest and non-optimized resistance strain detection design, is shown here to exhibit 13-memory states of high reproducibility and reliability. The related advantages in lower power consumption and limited device fatigue make our approach relevant for applications.Comment: Resistive random access memory-like (RRAM) effect is described. Multistate non-volatile ferroelastic-resistive memor

The magnetoelectrochemical switch

In the field of spintronics, the archetype solid-state two-terminal device is the spin valve, where the resistance is controlled by the magnetization configuration. We show here how this concept of spin-dependent switch can be extended to magnetic electrodes in solution, by magnetic control of their chemical environment. Appropriate nanoscale design allows a huge enhancement of the magnetic force field experienced by paramagnetic molecular species in solutions, which changes between repulsive and attractive on changing the electrodes' magnetic orientations. Specifically, the field gradient force created within a sub-100-nm-sized nanogap separating two magnetic electrodes can be reversed by changing the orientation of the electrodes' magnetization relative to the current flowing between the electrodes. This can result in a breaking or making of an electric nanocontact, with a change of resistance by a factor of up to 103. The results reveal how an external field can impact chemical equilibrium in the vicinity of nanoscale magnetic circuits

Nanotrench for nano and microparticle electrical interconnects

We present a simple and versatile patterning procedure for the reliable and reproducible fabrication of high aspect ratio (10 4 ) electrical interconnects that have separation distances down to 20 nm and lengths of several hundreds of microns. The process uses standard optical lithography techniques and allows parallel processing of many junctions, making it easily scalable and industrially relevant. We demonstrate the suitability of these nanotrenches as electrical interconnects for addressing micro and nanoparticles by realizing several circuits with integrated species. Furthermore, low impedance metal-metal low contacts are shown to be obtained when trapping a single metal-coated microsphere in the gap, emphasizing the intrinsic good electrical conductivity of the interconnects, even though a wet process is used. Highly resistive magnetite-based nanoparticles networks also demonstrate the advantage of the high aspect ratio of the nanotrenches for providing access to electrical properties of highly resistive materials, with leakage current levels below 1 pA. © 2010 IOP Publishing Ltd

Multi-state and non-volatile control of graphene conductivity with surface electric fields

Planar electrodes patterned on a ferroelectric substrate are shown to provide lateral control of the conductive state of a two-terminal graphene stripe. A multi-level and on-demand memory control of the graphene resistance state is demonstrated under low sub-coercive electric fields, with a susceptibility exceeding by more than two orders of magnitude those reported in a vertical gating geometry. Our example of reversible and low-power lateral control over 11 memory states in the graphene conductivity illustrates the possibility of multimemory and multifunctional applications, as top and bottom inputs remain accessible. (C) 2015 AIP Publishing LLC

Propriétés mécaniques du nickel utilisé en LIGA X et UV

International audienc

Design and test of new high Q microresonators fabricated by UV-LIGA

International audienceWe report in this paper the study of a new metallic microresonator realized by UV-LIGA technique. This kind of device is excited electrostatically and takes advantage of the contour modes or Lame-modes of the structure. Design methods of such device are presented and simulated with a Finite Element Program. Details on the microfabrication process are also presented. The vibration modes are detected with an optical bench set-up and preliminary electrical results are presented. A comparison between experiments and numerical predictions are finally discussed

Dynamic determination of Young's modulus of electroplated nickel used in LIGA technique

Mechanical properties of materials involved in the fabrication of new microactuators have to be well characterized in order to be used in CAD and for the simulation of microsystems. To achieve that goal, we present a study of the Young's modulus E of electroplated nickel used in the LIGA technique. This mechanical parameter was obtained by the analysis of vibration frequencies of free-clamped microcantilevers. The resonant frequencies of in-plane and out-of-plane flexural modes were measured with an optical bench. The experimental results are compared to the frequencies derived from a pure elastic finite element model. The variation of the boundary conditions, in particular the description of the clamped part of the devices, leads to a good agreement between the experimental and the simulation. The correlation between these two methods leads to the determination of the Young's modulus of the device. First results lead to an average value of 195 GPa, which is lower than the data reported for the bulk material. These results are in good agreement with our previous values obtained by steady-state bending tests and other works reported in the literature. E is insensitive to the direction of the excited mode which is characteristic of an isotropic behaviour of the electroplated metal

Conception de microrésonateurs à mode de Lamé

National audienc

Simulation and Characterization of High Q Microresonators Fabricated by UV – LIGA

Vol. 1, Chapter 7: Applications: MEMS, SensorsInternational audienceThis paper is devoted to a study on a new metallic microresonator realized by UV-LIGA technique. This device is excited electrostatically and takes advantage of the contour modes or Lamé-modes of the structure. Design methods of such device are presented and validated by the use of Finite Element Analysis (FEA). Details on the fabrication process are also exposed. The vibration modes are detected with an optical interferometer and preliminary results are presented. A comparison between experiments and numerical predictions are finally discussed