94 research outputs found
Skill policies for Scotland
This paper argues that skill formation is a life-cycle process and develops the
implications of this insight for Scottish social policy. Families are major
producers of skills, and a successful policy needs to promote effective families
and to supplement failing ones. Targeted early interventions have proven to be
very effective in compensating for the effect of neglect. Improvements in
traditional measures of school quality, tuition subsidies, company-sponsored
and public job training are unlikely to be as effective. We review the evidence
and present several policy recommendations
Response of a cold-electron bolometer on thz radiation from a long yba2cu3o7âδ bicrystal josephson junction
The response of the Cold-Electron Bolometers (CEBs), integrated into a 2-D array of dipole antennas, has been measured by irradiation from YBa2Cu3O7âδ (YBCO) 50 \ub5m long Josephson junction into the THz region at frequencies from 0.1 to 0.8 THz. The possibility of controlling the amplitude-frequency characteristic is demonstrated by the external magnetic field in the traveling wave regime of a long Josephson junction. The YBCO junction has been formed on the bicrystal Zr1âxYxO2 (YSZ) substrate by magnetron sputtering and etching of the film. CEBs have been fabricated using an Al multilayer structure by a self-aligned shadow evaporation technique on Si substrate. Both receiver and oscillator have been located inside the same cryostat at 0.3 K and 2.7 K plates, respectively
Ferromagnetic semiconductors
The current status and prospects of research on ferromagnetism in
semiconductors are reviewed. The question of the origin of ferromagnetism in
europium chalcogenides, chromium spinels and, particularly, in diluted magnetic
semiconductors is addressed. The nature of electronic states derived from 3d of
magnetic impurities is discussed in some details. Results of a quantitative
comparison between experimental and theoretical results, notably for Mn-based
III-V and II-VI compounds, are presented. This comparison demonstrates that the
current theory of the exchange interactions mediated by holes in the valence
band describes correctly the values of Curie temperatures T_C magnetic
anisotropy, domain structure, and magnetic circular dichroism. On this basis,
chemical trends are examined and show to lead to the prediction of
semiconductor systems with T_C that may exceed room temperature, an expectation
that are being confirmed by recent findings. Results for materials containing
magnetic ions other than Mn are also presented emphasizing that the double
exchange involving hoping through d states may operate in those systems.Comment: 18 pages, 8 figures; special issue of Semicon. Sci. Technol. on
semiconductor spintronic
Spintronics: Fundamentals and applications
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.Comment: invited review, 36 figures, 900+ references; minor stylistic changes
from the published versio
V. F. Masterovâs school and fullerene research at the department of experimental physics, St. Petersburg State Technical University
Excitation and De-excitation Cross Sections for Light-Emitting Nanoclusters in Rare EarthâDoped Silicon
A technique for manufacturing passive HF and UHF elements based on high-temperature superconducting YBCO films: Parameters of test samples
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