Sheldon Schultz

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.

Experimental Evidence For A New Interpretation Of Local-moment Resonances In Metals

Abstract: The transmission and two reflection spin-resonance signals for single-crystal $\mathrm{Ag}\mathrm{Gd}$ are shown to have the same crystal-field parameter, and hence are attributable to an isolated local moment. This identification illustrates why $S$-state resonance data need re-examination. The ratio of the averages of $J(k, {k}^{\ensuremath{'}})$ appropriate to the exchange field and relaxation rate of the local moment is \ensuremath{\simeq} 3 which may be difficult to interpret within the framework of presently accepted models.

Search for new superconductors in the Y-Ni-B-C system

Abstract: We have searched for superconductivity in a wide variety of stoichiometries in the Y-Ni-B-C system, using Yx(NiB)Cy phase spread alloy thin films and the magnetic field modulated microwave absorption technique. The superconducting critical temperature (Tc) varies with the stoichiometry, showing the highest Tc for a Y/Ni ratio of 1/2, attributed to the YNi2B2C phase. We found no other superconducting phases with a Tc higher than 10 K. Furthermore, a search in YxNiB(C1−zNz)y and YxNiBNy phase spread alloys showed no superconductivity.

Photonic band gap resonators for high energy accelerators

Abstract: We have proposed that a new type of microwave resonator, based on photonic band gap (PBG) structures, may be particularly useful for high energy accelerators. We provide an explanation of the PBG concept and present data which illustrate some of the special properties associated with such structures. Further evaluation of the utility of PBG resonators requires laboratory testing of model structures at cryogenic temperatures, and at high fields. We provide a brief discussion of our test program, which is currently in progress. >

Experimental confirmation of negative phase change in negative index material planar samples

Abstract: We use far-field range measurements to determine and confirm the negative phase change through a planar negative index material as a function of frequency. The metamaterial is composed of wires and split ring resonators. At frequencies for which the surface impedance Z∕Z0=1, we determine the index (n) from the measured phase change (relative to a vacuum) and via numerical simulation. In addition to confirming the simulated negative phase change at the frequency where n=−1, we find good agreement with prior Snell’s law measurements from n=−2.5 to −0.5. This illustrates that measuring the phase change of the transmitted signal can be a practical means of identifying the existence of negative index in planar test samples.

Identification of objects using plasmon resonant particles

Abstract: A method and apparatus for identifying an object having a pattern of plasmon resonant particles (PREs) distributed in or on the object are disclosed. In the method, a field containing the pattern is illuminated, and one or more spectral emission characteristics of the light-scattering particles in the field are detected. From this data, an image of positions and spectral characteristic values in the field is constructed, allowing PREs with a selected spectral signature to be discriminated from other light-scattering entities, to provide information about the field. The image may be compared to a database of reference images to identify or validate the object.

Surface plasmon subwavelength optics

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.

Spintronics: Fundamentals and applications

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.

Experimental Verification of a Negative Index of Refraction

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.

Plasmonics for improved photovoltaic devices

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.

Controlling 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.