Electricity and Magnetism,Volume 1: Third Edition,Electricity and Magnetism,Volume 2: Third Edition,by B.I. Bleaney and B. Bleaney

During the last decade the term ‘spin glass’ has become prominent in the literature on magnetism. It refers to magnetic alloys where the spins on the impurities become locked or frozen into random orientations below a characteristic temperature T ₀. In this article the properties of spin glasses are described with particular reference to the two archetypal examples AuFe and CuMn. Interest in spin glasses was mainly stimulated by some a.c. susceptibility measurements which showed sharp, cusp-like peaks, accurately defining T ₀ and suggesting that some type of phase transition was occurring. The Mossbauer effect and the anomalous Hall effect also showed clear features at T ₀ supporting this viewpoint. But measurements of the electrical resistivity and ‘specific heat’, here usually meaning the molar heat capacity, also the remanence, magnetic hysteresis and time-dependent effects observed in spin glasses were difficult to reconcile with a phase transition approach. This article discusses the results obtained from the very wide variety of experimental techniques which have been used to investigate spin glasses, and also deals with some of the important theoretical concepts which have arisen out of these studies. Then follows a short account of the many systems which have been found to exhibit spin glass behaviour and which suggest that it is a widespread magnetic state of matter. Lastly, an example is given which shows that some of the ideas of spin glasses are applicable to problems outside the sphere of magnetic alloys.     

Probability,Random Processes,and Statistical Analysis,by H. Kobayashi,B.L. Mark and W. Turin

This article describes the scientific objectives, the scientific and operational plans and the observational programme of the international Atlantic Tropical Experiment in which some 70 countries pclrticipated during Jun-September 1974. The main aim waa to make, for the first time, an intensive study of the structure, evolution and transport properties of tropical weather systems and their role in the global circulation of the atmosphere as a whole. Some preliminary results are described but it will be two or three years before the vast mass of data is fully processed and analysed and made available in the form of validated data sets for detailed researoh studies and for input to numerical models. However, there is already good reason to believe that the major scientific objectives of the experiment will be achieved and that the knowledge gained will lead to improved weather forecasting both in the tropics, and in middle latitudes where accurate predictions for more than about three days ahead may not be possible without taking into account the import of heat and moiature from the tropical oceans through the large convective clouds of the tropical atmosphere.     

Spectroscopy of 13B, 14B, 15B and 16B using multi-nucleon transfer reactions

New information has been obtained on excited states of the neutron-rich boron isotopes ¹⁴B, ¹⁵B and ¹⁶B, using the reactions ¹²C(¹⁴C,¹²N)¹⁴B, ¹³C(¹⁴C,¹²N)¹⁵B and ¹⁴C(¹⁴C,¹²N)¹⁶B at about 24 MeV/A. The mass excess of ¹⁶B has been measured for the first time, it is 37.08(6) MeV. This means that ¹⁶B is unbound by only 0.04(6) MeV. Furthermore, the nucleus ¹³B has been investigated with the four reactions ¹⁶O(¹⁴C,¹⁷F), ¹²C(¹⁴C,¹³N), ¹²C(¹³C,¹²N) and ¹²C(¹⁵N,¹⁴O). Choosing different target-projectile combinations, it was possible to populate states with different selectivity. New states are observed in ¹³B at excitation energies above the threshold for two-neutron decay. Received: 27 December 1999 / Revised version: 11 February 2000     

Metamaterials: Critique and Alternatives,by B.A. Munk

Relativistic electrons undergoing centripetal acceleration in a synchrotron emit a highly collimated forward cone of continuous radiation. The continuum extends from the extreme ultraviolet to the radiofrequency region for electrons of GeV energies and is very suitable for absorption spectroscopy in the region of the ultraviolet extending from a few tens of ågströms to 2000 Å. This paper discusses some properties of synchrotron radiation of interest to spectroscopists and some experimental difficulties associated with ultraviolet spectroscopy. Examples we given of ultraviolet spectra of free atoms and molecules and also of solids obtained recently with synchrotron radiation.     

B.c.c.-f.c.c. allotropy, F-bands,and metallization in xenon and krypton

APW-Xα calculations of a f.c.c.-b.c.c. phase transition in Xe prior to metallization give P ? 950 kbar, contrary to the 820 kbar result of Hama and Matsui; their use of non-touching APW spheres (f.c.c.) may be the crucial difference. Hartree-Fock plus correlation calculations in Kr indicate that f-bands play no role in rare gas crystal metallization.