# Showing papers in "Advances in Physics in 1993"

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TL;DR: In this paper, a review is concerned with quantum confinement effects in low-dimensional semiconductor systems, focusing on the optical properties, including luminescence, of nanometre-sized microcrystals.

Abstract: This review is concerned with quantum confinement effects in low-dimensional semiconductor systems. The emphasis is on the optical properties, including luminescence, of nanometre-sized microcrysta...

1,030 citations

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TL;DR: In this article, anisotropic magnetic anisotropies and exchange interactions in ultrathin metallic magnetic films are discussed. But the authors do not consider the magnetic exchange interaction in this paper.

Abstract: (1993). Ultrathin metallic magnetic films: magnetic anisotropies and exchange interactions. Advances in Physics: Vol. 42, No. 5, pp. 523-639.

412 citations

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TL;DR: In this article, the structure and bonding of the Si(111)-7 × 7 and Si(100)-2 × 1 surfaces are described together with the adsorption and desorption of hydrogen from these surfaces.

Abstract: This article focuses on recent scanning tunnelling microscopy studies that have led to an improved understanding of the interaction of hydrogen with silicon surfaces. The structure and bonding of the Si(111)-7 × 7 and Si(100)-2 × 1 surfaces are described together with the adsorption and desorption of hydrogen from these surfaces. The role of hydrogen in the passivation of silicon surfaces and silicon chemical vapour deposition are also discussed.

184 citations

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TL;DR: In this article, analytical and numerical results derived from the Bethe ansatz solution of the n-channel Kondo model of arbitrary spin S as a function of temperature, external field, impurity spin S and the number of channels n were discussed in the context of magnetic impurities.

Abstract: We review analytical and numerical results derived from the Bethe ansatz solution of the n-channel Kondo model of arbitrary spin S as a function of temperature, external field, impurity spin S and the number of channels n. Three situations have to be distinguished: (i) If n = 2S the conduction electrons exactly compensate the impurity spin into a singlet at low temperatures, (ii) if n 2S the impurity spin is said to be overcompensated giving rise to critical behaviour. The results are discussed in the context of magnetic impurities, e.g. Fe, Cr and Tm in simple metals, the quadrupolar Kondo effect, an impurity spin embedded in the Takhtajan-Babujian Heisenberg model and electron assisted-tunnelling of an atom in a double-well potential.

99 citations

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TL;DR: The phase transitions and critical properties of two types of inhomogeneous systems are reviewed in this article, where the authors combine mean field theory, scaling considerations, conformal transformations and perturbation theory.

Abstract: The phase transitions and critical properties of two types of inhomogeneous systems are reviewed. In one case, the local critical behaviour results from the particular shape of the system. Here scale-invariant forms like wedges or cones are considered as well as general parabolic shapes. In the other case the system contains defects, either narrow ones in the form of lines or stars, or extended ones where the couplings deviate from their bulk values according to power laws. In each case the perturbation may be irrelevant, marginal or relevant. In the marginal case one finds local exponents which depend on a parameter. In the relevant case unusual stretched exponential behaviour and/or local first-order transitions appear. The discussion combines mean field theory, scaling considerations, conformal transformations and perturbation theory. A number of examples are Ising models for which exact results can be obtained. Some walks and polymer problems are considered, too.

85 citations

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TL;DR: In this paper, the use of computer simulations and analogue simulations to explore the physics of multi-particle systems is demonstrated. And the impact of computer technology and the ability to manufacture essentially monodisperse polymer microspheres with well controlled properties (such as magnetic moment, charge, size, porosity and density) is illustrated.

Abstract: The complementary use of computer simulations and analogue simulations to explore the physics of multiparticle systems is demonstrated. Applications to problems of current interest (e.g. non-equilibrium pattern formation, granular flow, and the physics of disordered materials) are emphasized. The ability to describe complex systems in quantitative terms using concepts such as fractal geometry and scaling and the development of new theoretical approaches has led to substantial progress during the past ten years, but we still seem quite far from a general theoretical understanding of many of the problems discussed in this review. The impact of computer technology and the ability to manufacture essentially monodisperse polymer microspheres with well controlled properties (such as magnetic moment, charge, size, porosity and density) is illustrated.

62 citations

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TL;DR: In this article, the authors present an extensive review of the thermal properties associated with the phase transitions related to these liquid-crystal hexatic phases, and demonstrate that hexatic order is the only symmetry-breaking field associated with hexatic-B and smectic-I phases.

Abstract: Ever since the hexatic phase was proposed more than 14 years ago in the context of two-dimensional melting theory, the concept of hexatic order has offered unique insight into the nature of several liquid-crystal phases, namely the hexatic-B, smectic-I and smectic-F phases. Moreover, these liquid-crystal phases have offered numerous opportunities to explore and investigate the nature of hexatic order and the related phase transitions. In this paper we present an extensive review of the thermal properties associated with the phase transitions related to these liquid-crystal hexatic phases. Although both electron-beam and X-ray diffraction studies have indicated the importance of hexatic ordering in understanding these phases, the existing experimental data from numerous thermal measurements fail to demonstrate that hexatic order, which can be represented by a complex variable and therefore belongs to the XY universality class, is the only symmetry-breaking field associated with the hexatic-B—smect...

46 citations

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TL;DR: In this paper, a detailed comparison of experimental scattering rates obtained by different measuring techniques and of experimental and theoretical scattering rates in various metals was made. But the experimental results were not considered.

Abstract: Ballistic effects are reviewed which allow the determination of scattering rates of local groups of electrons on the Fermi surface of metals. Significant progress in our understanding of scattering mechanisms has been made in the last decade through the improved capabilities of high frequency size effects. The anisotropy of electron phonon scattering has been shown to be a general rule; the electron-electron scattering rate has been measured not only in transition metals, but also in simple metals; new effects have been observed from scattering at the sample surface, supporting theoretical calculations of the electric field distribution near the surface. A detailed comparison is made of experimental scattering rates obtained by different measuring techniques and of experimental and theoretical scattering rates in various metals.

44 citations

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TL;DR: The use of ordered microstructures makes it possible to obtain new (including quantitative) information on elementary pinning forces and on methods of their summation and, on the other hand, to observe interesting effects based on the coherent behaviour of Abrikosov vortices in them.

Abstract: The use of ordered microstructures makes it possible, on the one hand, to obtain new (including quantitative) information on elementary pinning forces and on methods of their summation and, on the other hand, to observe interesting effects based on the coherent behaviour of Abrikosov vortices in them. Some progress in these fields of research, has been achieved at the present time. We believe that today the study of quasiperiodic structures and, in particular, pinning in these structures, is also a topical problem. This is because these structures are an intermediate case between fully ordered superconducting lattices and the chaotic system of pinning centres which exists in ordinary superconductors. One of the basic objectives of this review was to demonstrate the existence of interesting problems from the viewpoints of both fundamental and applied physics in this area. It should also be stated that because of the rapid development of technology it is hoped that soon it will be possible to creat...

20 citations