Topic
Conductance
About: Conductance is a research topic. Over the lifetime, 8088 publications have been published within this topic receiving 235961 citations.
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TL;DR: In this article, the spin-polarized quasiparticle transport in ferromagnet-$d$-wave-superconductor junctions with the same interface was studied.
Abstract: Within a scattering framework, a theoretical study is presented for the spin-polarized quasiparticle transport in ferromagnet--$d$-wave-superconductor junctions with ${110}$ interface. We find that the subgap conductance behaviors are qualitatively different from a nonmagnetic case, due to the modification of Andreev reflection by the exchange field in the ferromagnet, and can also be significantly different from those of a ferromagnet--$s$-wave junction because of the sign change of the d-wave order parameter along the ${110}$ direction of the crystal. For a ballistic ferromagnet--$d$-wave-superconductor junction, a zero-bias conductance minimum is achieved. In addition, a conductance maximum at finite bias can also be evolved by interfacial scattering. For a normal-metal--ferromagnet--$d$-wave-superconductor junction, conductance resonances are predicted.
113 citations
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TL;DR: High resolution experiments of the alamethicin pore demonstrate the existence of a further pore state at low conductance values, which seems to be impermeable to Ca2+, Cl, Tris-H+ and Hepes-, whereas the higher conductance states are not.
113 citations
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TL;DR: The conductance of lipid membranes in the presence of nonactin is changed by the adsorption of small amounts of ionic and zwitterionic surfactants, which is accurately accounted for by the variation in total potential across the membrane interface.
113 citations
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TL;DR: It is shown that the conductance of such a junction, in the clean limit and at low temperature, changes from oscillatory to a monotonically decreasing function of d beyond a critical J, which leads to the possible realization of a magnetic switch using these junctions.
Abstract: We study the transport properties of the Dirac fermions with a Fermi velocity v(F) on the surface of a topological insulator across a ferromagnetic strip providing an exchange field J over a region of width d. We show that the conductance of such a junction, in the clean limit and at low temperature, changes from oscillatory to a monotonically decreasing function of d beyond a critical J. This leads to the possible realization of a magnetic switch using these junctions. We also study the conductance of these Dirac fermions across a potential barrier of width d and potential V-0 in the presence of such a ferromagnetic strip and show that beyond a critical J, the criteria of conductance maxima changes from chi = eV(0)d/(h) over barv(F) = n pi to chi = (n + 1/2)pi for integer n. We point out that these novel phenomena have no analogs in graphene and suggest experiments which can probe them.
113 citations
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TL;DR: In this paper, the second moment of the distribution of the Tn's was measured by measuring the voltage dependence of the conductance s √GyV 2 IyV 2 d d and showed that the fluctuation pattern changes randomly between contact configurations and that the amplitude of the fluctuations is suppressed for conductance values near G0.
Abstract: Metallic contacts consisting of only a few atoms can be obtained using scanning tunneling microscopy or mechanically controllable break junction [1] techniques. The electrical conductance through such contacts is described in terms of electronic wave modes by the Landauer-Buttiker formalism [2]. Each of the N modes forms a channel for the conductance, with a transmission probability Tn between 0 and 1. The total conductance is given by the sum over these channels G › P N›1 TnG0, where G0 › 2e 2 yh is the quantum of conductance. By recording histograms of conductance values [3] for contacts of simple metals (Na, Au), a statistical preference was observed for conductances near integer values. This statistical preference was interpreted as an indication that transmitted modes in the most probable contacts are completely opened (Tn › 1, i.e., saturation of channel transmission), in analogy with the conductance quantization observed in 2D electron gas devices [4]. Here, we test this interpretation by performing a new type of measurement giving access to the second moment of the distribution of the Tn’s. The atomic contacts are formed by breaking a gold wire at low temperatures, and then finely adjusting the size of the contact between the fresh fracture surfaces using a piezoelectric element [1]. Figure 1 shows the differential conductance, ›Iy›V measured as a function of bias voltage for three atomic-size contacts with different conductance values, using a modulation voltage eV ? kBu (with u the temperature). For each contact, both of the curves for increasing and decreasing bias voltage are given. Measurements such as those of Fig. 1 suggest that the fluctuation pattern changes randomly between contact configurations and that the amplitude of the fluctuations is suppressed for conductance values near G0. In order to establish such a relation, it is necessary to statistically average over a large number of contacts. We do this by measuring the voltage dependence of the conductance s›Gy›V › › 2 Iy›V 2 d and
112 citations