Differential resistance

On the other hand, some work on the topic considers the presence of negative differential resistance in the current-voltage characteristics and the possibility of a coulomb... 

According to the literature [21], all reported electrochemical oscillations can be classified into four classes depending on the roles of the true electrode potential (or Helmholtz-layer potential, E). Electrochemical oscillations in which E plays no essential role and remains essentially constant are known as strictly potentiostatic (Class I) oscillations, which can be regarded as chemical oscillations containing electrochemical reactions. Electrochemical oscillations in which E is involved as an essential variable but not as the autocatalytic variable are known as S-NDR (Class II) oscillations, which arise from an S-shaped negative differential resistance (S-NDR) in the current density (/) versus E curve. Oscillations in which E is the autocatalytic variable are knovm as N-NDR (Class III) oscillations, which have an N-shaped NDR. Oscillations in which the N-NDR is obscured by a current increase from another process are knovm as hidden N-NDR (HN-NDR Class IV) oscillations. It is known that N-NDR oscillations are purely current oscillations, whereas HN-NDR oscillations occur in both current and potential. The HN-NDR oscillations can be further divided into three or four subcategories, depending on how the NDR is hidden. 

Switzer, J. A., Maune, B. M., Raub, E. R. and Bohannan, E. W. (1999) Negative differential resistance in electrochemicaDy self-assembled layered nanostructures. J. Phys. Chem. B, 103, 395-398. 

Among the two-terminal devices that can be imagined for UE [capacitors, inductors, rectifiers, negative differential resistance (NDR) devices], the simplest is a molecular wire, that is, a molecule capable of conducting electricity a nanoconductor or, equivalently, a nanoresistor. Even the most conductive of molecular wires has a minimum resistance. 

Chen J, Reed MA, Rawlett AM, Tour JM (1999) Large on-off ratios and negative differential resistance in a molecular electronic device. Science 286 1550-1552... 

In addition and importantly, even in non-active junctions, when the electrode Fermi level matches the molecular bridge energy levels, resonance phenomena can generate electrical behaviours similar to those of conventional electronic devices, such as rectification [86-89] and negative differential resistance (NDR) [90, 91]. 

Wassel RA, Credo GM, FuiererRR, Feldheim DL, Gorman CB (2004) Attenuating negative differential resistance in an electroactive self-assembled monolayer-based junction. J Am Chem Soc 126 295-300... 

Le JD, He Y, Hoye TR, Mead CC, Kiehl RA (2003) Negative differential resistance in a bilayer molecular junction. Appl Phys Lett 83 5518... 

Molecular Rectifiers and Negative Differential Resistance Devices. 234... 

Figure 12. Synthetic route to a molecular device that bears functionality for electron capture. This nitroaniline exhibits negative differential resistance.

Our simple calculation thus reflects the well-known result [1-6] that the differential resistance measured in the tunneling current through an STM tip is proportional to the local DOS of the molecule at the tip. In this section, we did not use any concrete model for the Hamiltonian, the only assumption we needed to make was that the molecule is much more strongly coupled to the metal surface than to the tip, which, at least for metallic surfaces, is always the case. 

Lyo, I. W., and Avouris, Ph. (1989). Negative differential resistance on the atomic scale Implications for atomic scale devices. Science 245, 1369-1371. 

In Fig. 4.3.3b we present a V — I curve with a turning point and a negative differential resistance region with current saturation, computed for the same values of parameters Ni, A, cq as in Fig. 4.3.3a. This V—I curve corresponds to the upper and the middle solution branches. The range of parameters in which the high current solutions exist is again evaluated below, via an asymptotic treatment for /— oo. 

Stability of the described solution branches (the middle branch with negative differential resistance is expected to be unstable). 

Examination of flame-etched surfaces revealed only scattered torus-shaped ring and moat structures, 100-200m in diameter. These features probably result from differential resistance of anthraxolite and rare impurities to oxidation. 

Our samples were fabricated with a multistep process described elsewhere [10]. The samples had structure Co(20)/Cu(10)/Co(2.5), where thicknesses are in nm. To minimize dipolar coupling between the Co layers, only the Cu(10)/ Co(2.5) layers were patterned into a nanopillar with approximate dimensions 140 x 70 nm. We measured differential resistance, dV/dl, at 295 K with four-probes and lock-in detection, adding an ac current of amplitude 20 //,A at... 

In this paper, we report measurements of the low temperature differential resistance of mesoscopic FS junctions. We observe asymmetries in the differential resistance even in the absence of an external magnetic field. These asymmetries are associated with spin-polarized tunneling into the superconductor, with the splitting of the quasi-particle density of states in the superconductor arising from the magnetic field generated by the ferromagnetic elements. 

Figure 3(a) shows the results of our calculations of the normalized differential resistance using Eqn.(3) with H = 0, for a number of different combinations of Z and P. For Z 0 and P = 0, we recover the usual BTK result, in that the resistance at zero bias drops to half the normal state value. For Z = 0 and P = 0.5, the resistance at zero bias is exactly the same as the normal state resistance, while for Z = 0.5 and P = 0, it is slightly larger. As both Z and P are increased, the resistance of the sample rises above the normal state resistance RN, but Z and P affect the differential resistance in different ways... 

Fig. 4. Differential resistance dV/dl of the sample shown in Fig. 1(a), as a function of dc current Idc, at different values of the applied magnetic field H. The temperature...

Fig. 5. Numerical simulation of the differential resistance of a FS interface, including charge imbalance, as described in the text. Solid line, spin-polarized BTK model with charge-imbalance dashed line, spin-polarized BTK model without charge imbalance. The other parameters used in the simulation are P = 0.3, Z = 0.3, and H = 0.1 A.

The differential resistance of mesoscopic ferromagnet/superconductor junctions shows a number of features associated with the injection of spin-polarized carriers into the superconductor. In particular, large peaks are observed at currents corresponding to the superconducting gap voltage. These peaks are... 

Fig. 3. Effective transferred charge (a), differential noise (b), and differential resistance (inset) vs voltage at = 0 (solid lines) and

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