Author
Sheldon Schultz
Other affiliations: University of California, École Polytechnique Fédérale de Lausanne
Bio: Sheldon Schultz is an academic researcher from University of California, San Diego. The author has contributed to research in topics: Magnetization & Plasmon. The author has an hindex of 43, co-authored 135 publications receiving 26175 citations. Previous affiliations of Sheldon Schultz include University of California & École Polytechnique Fédérale de Lausanne.
Papers published on a yearly basis
Papers
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TL;DR: It is shown that the case of an infinite magnetic strip can be reduced to a one-dimensional eigenvalue problem which is solved numerically, yielding insight into the more difficult rectangular case.
Abstract: Approximate methods for obtaining the magnetostatic mode spectrum of thin rectangular samples have been known for some time. However, our experimental results from lithographic arrays of submicron Permalloy particles show that these methods perform relatively poorly if the (in-plane) applied field is not large compared to 4\ensuremath{\pi}${\mathit{M}}_{\mathit{s}}$. We present an improved method for finding the spectrum that takes into account both the elliptical character of the mode precession and sample edge effects. We show that the case of an infinite magnetic strip can be reduced to a one-dimensional eigenvalue problem which we solve numerically, yielding insight into the more difficult rectangular case. Effects of the nonuniform demagnetization field on the spatial patterns and frequencies of the modes are also studied.
38 citations
TL;DR: The authors' data are not compatible with the models based only on magnetic fluctuations which predict an ESR linewidth of a few hundred Oe at such high temperatures, and other suggested explanations for the absence of a Cu[sup 2+] ESR signal are discussed.
Abstract: One unresolved question in the high-temperature superconductors and their copper oxide parent compounds is the absence of a Cu[sup 2+] electron-spin-resonance (ESR) signal even at temperatures well above the Neel temperature. We have extended the measurements up to 1150 K in both single crystals and ceramic pellets of La[sub 2]CuO[sub 4+[delta]], 0[approx lt][delta][approx lt]0.12, and no ESR signal has been observed. Our data are not compatible with the models based only on magnetic fluctuations which predict an ESR linewidth of a few hundred Oe at such high temperatures. Other suggested explanations for the absence of a Cu[sup 2+] ESR signal are discussed.
35 citations
34 citations
TL;DR: In this article, the decay of the magnetization with time does not follow a simple log t relation, and an empirical model which allows one to relate values of coercive field, H c, obtained with a 60 Hz B-H looper, to that measured with a slow VSM field cycle is presented.
Abstract: We report on magnetization time decay data on several commercial and experimental tapes (γ-Fe 2 O 3 , Co-doped, and Co-Cr) measured at room temperature between 1s and 104s. We found that the decay of the magnetization with time does not follow a simple log t relation. We analyze our data with an empirical model which allows one to relate values of coercive field, H c , obtained with a 60 Hz B-H looper, to that measured with a slow VSM field cycle. The methodology we have developed appears to have promise as a means of correlating data over ten orders of magnitude of time from 10-6s to 104s.
33 citations
TL;DR: In this article, the authors present an experimental study of the thermally activated switching of the magnetization of individual isolated γ-Fe2O3 particles and find that the switching is thermally assisted, but cannot be described by hopping over a single energy barrier.
Abstract: We present an experimental study of the thermally activated switching of the magnetization of individual isolated γ‐Fe2O3 particles. These particles are prolate ellipsoids ∼3000 A long and 650 A wide. The measured angular dependence of the switching field, Hs(θ), is consistent at large angles with a uniform rotation, but as θ approaches zero, other modes of reversal appear possible, and most likely the mode of reversal is curling. By measuring the probability of reversal of the moment as a function of time and applied magnetic field at T∼300 K, we found that the switching was thermally assisted, but couldn’t be described by hopping over a single energy barrier. Our results indicate that the dynamics of switching are described by a complex path in the energy landscape.
32 citations
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TL;DR: By altering the structure of a metal's surface, the properties of surface plasmons—in particular their interaction with light—can be tailored, which could lead to miniaturized photonic circuits with length scales that are much smaller than those currently achieved.
Abstract: Surface plasmons are waves that propagate along the surface of a conductor. By altering the structure of a metal's surface, the properties of surface plasmons--in particular their interaction with light--can be tailored, which offers the potential for developing new types of photonic device. This could lead to miniaturized photonic circuits with length scales that are much smaller than those currently achieved. Surface plasmons are being explored for their potential in subwavelength optics, data storage, light generation, microscopy and bio-photonics.
10,689 citations
TL;DR: Spintronics, or spin electronics, involves the study of active control and manipulation of spin degrees of freedom in solid-state systems as discussed by the authors, where the primary focus is on the basic physical principles underlying the generation of carrier spin polarization, spin dynamics, and spin-polarized transport.
Abstract: Spintronics, or spin electronics, involves the study of active control and manipulation of spin degrees of freedom in solid-state systems. This article reviews the current status of this subject, including both recent advances and well-established results. The primary focus is on the basic physical principles underlying the generation of carrier spin polarization, spin dynamics, and spin-polarized transport in semiconductors and metals. Spin transport differs from charge transport in that spin is a nonconserved quantity in solids due to spin-orbit and hyperfine coupling. The authors discuss in detail spin decoherence mechanisms in metals and semiconductors. Various theories of spin injection and spin-polarized transport are applied to hybrid structures relevant to spin-based devices and fundamental studies of materials properties. Experimental work is reviewed with the emphasis on projected applications, in which external electric and magnetic fields and illumination by light will be used to control spin and charge dynamics to create new functionalities not feasible or ineffective with conventional electronics.
9,158 citations
TL;DR: These experiments directly confirm the predictions of Maxwell's equations that n is given by the negative square root ofɛ·μ for the frequencies where both the permittivity and the permeability are negative.
Abstract: We present experimental scattering data at microwave frequencies on a structured metamaterial that exhibits a frequency band where the effective index of refraction (n) is negative. The material consists of a two-dimensional array of repeated unit cells of copper strips and split ring resonators on interlocking strips of standard circuit board material. By measuring the scattering angle of the transmitted beam through a prism fabricated from this material, we determine the effective n, appropriate to Snell's law. These experiments directly confirm the predictions of Maxwell's equations that n is given by the negative square root of epsilon.mu for the frequencies where both the permittivity (epsilon) and the permeability (mu) are negative. Configurations of geometrical optical designs are now possible that could not be realized by positive index materials.
8,477 citations
TL;DR: Recent advances at the intersection of plasmonics and photovoltaics are surveyed and an outlook on the future of solar cells based on these principles is offered.
Abstract: The emerging field of plasmonics has yielded methods for guiding and localizing light at the nanoscale, well below the scale of the wavelength of light in free space. Now plasmonics researchers are turning their attention to photovoltaics, where design approaches based on plasmonics can be used to improve absorption in photovoltaic devices, permitting a considerable reduction in the physical thickness of solar photovoltaic absorber layers, and yielding new options for solar-cell design. In this review, we survey recent advances at the intersection of plasmonics and photovoltaics and offer an outlook on the future of solar cells based on these principles.
8,028 citations
TL;DR: This work shows how electromagnetic fields can be redirected at will and proposes a design strategy that has relevance to exotic lens design and to the cloaking of objects from electromagnetic fields.
Abstract: Using the freedom of design that metamaterials provide, we show how electromagnetic fields can be redirected at will and propose a design strategy. The conserved fields-electric displacement field D, magnetic induction field B, and Poynting vector B-are all displaced in a consistent manner. A simple illustration is given of the cloaking of a proscribed volume of space to exclude completely all electromagnetic fields. Our work has relevance to exotic lens design and to the cloaking of objects from electromagnetic fields.
7,811 citations