Charge Density Wave Ratchet

We propose to operate a locally-gated charge density wave as an electron pump. Applying an oscillating gate potential with frequency $f$ causes equally spaced plateaux in the sliding charge density wave current separated by $\Delta I=2eNf,$ where $N$ is the number of parallel chains. The effects of thermal noise are investigated.Comment: To be published in Applied Physics Letter

Domain wall switching: optimizing the energy landscape

It has recently been suggested that exchange spring media offer a way to increase media density without causing thermal instability (superparamagnetism), by using a hard and a soft layer coupled by exchange. Victora has suggested a figure of merit xi = 2 E_b/mu_0 m_s H_sw, the ratio of the energy barrier to that of a Stoner-Wohlfarth system with the same switching field, which is 1 for a Stoner-Wohlfarth (coherently switching) particle and 2 for an optimal two-layer composite medium. A number of theoretical approaches have been used for this problem (e.g., various numbers of coupled Stoner-Wohlfarth layers and continuum micromagnetics). In this paper we show that many of these approaches can be regarded as special cases or approximations to a variational formulation of the problem, in which the energy is minimized for fixed magnetization. The results can be easily visualized in terms of a plot of the energy as a function of magnetic moment m_z, in which both the switching field [the maximum slope of E(m_z)] and the stability (determined by the energy barrier E_b) are geometrically visible. In this formulation we can prove a rigorous limit on the figure of merit xi, which can be no higher than 4. We also show that a quadratic anistropy suggested by Suess et al comes very close to this limit.Comment: Acccepted for proceedings of Jan. 2007 MMM Meeting, paper BE-0

Brandstofcellen

A review with 9 refs. The topics include: principle; low-temp. (cool) combustion; high-temp. (hot) combustion; applications of fuel cells; and cheaper fuel cells. [on SciFinder (R)

Inference for threshold models with variance components from the generalized linear mixed model perspective

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Strong Effects of Weak Localization in Charge Density Wave/Normal Metal Hybrids

Collective transport through a multichannel disordered conductor in contact with charge-density-wave electrodes is theoretically investigated. The statistical distribution function of the threshold potential for charge-density wave sliding is calculated by random matrix theory. In the diffusive regime weak localization has a strong effect on the sliding motion.Comment: To be published in Physical Review

Letter from Seine Bolks to Karel de Moen

A letter of the Rev. Seine Bolks to the Rev. Karel de Moen, explaining why he and his people decided to settle in the Holland Colony. His letter is not as extensive as Vander Meulen\u27s and Van Raalte\u27s, but is important nevertheless.https://digitalcommons.hope.edu/vrp_1840s/1211/thumbnail.jp