We report that a layered iron-based compound LaOFeAs undergoes superconducting transition under doping with F- ions at the O2- site. The transition temperature (Tc) exhibits a trapezoid shape dependence on the F- content, with the highest Tc of ∼26 K at ∼11 atom %.

Iron-Based Layered Superconductor La[O1-xFx]FeAs (x = 0.05−0.12) with Tc = 26 K

http://aerg.canberra.edu.au/library/sex_general/2002_Devlin_Nagahama_sex_determination_in_fish_review.pdf

Sex determination and sex differentiation in fish: an overview of genetic, physiological, and environmental influences

This review presents a summary and evaluation of the experimental properties of unconventional superconductivity in ${\mathrm{Sr}}_{2}{\mathrm{RuO}}_{4}$ as they were known in the spring of 2002. At the same time, the paper is intended to be useful as an introduction to the physics of spin-triplet superconductivity. First, the authors show how the normal-state properties of ${\mathrm{Sr}}_{2}{\mathrm{RuO}}_{4}$ are quantitatively described in terms of a quasi-two-dimensional Fermi liquid. Then they summarize its phenomenological superconducting parameters in the framework of the Ginzburg-Landau model, and discuss the existing evidence for spin-triplet pairing. After a brief introduction to the vector order parameter, they examine the most likely symmetry of the triplet state. The structure of the superconducting energy gap is discussed, as is the effect of symmetry-breaking magnetic fields on the phase diagram. The article concludes with a discussion of some outstanding issues and desirable future work. Appendixes on additional details of the normal state, difficulty in observing the bulk Fermi surface by angle-resolved photoemission, and the enhancement of superconducting transition temperature in a two-phase ${\mathrm{Sr}}_{2}{\mathrm{RuO}}_{4}\ensuremath{-}\mathrm{Ru}$ system are included.

The superconductivity of Sr 2 RuO 4 and the physics of spin-triplet pairing

We report superconductivity in an iron-based layered oxy-pnictide LaOFeP. LaOFeP is composed of an alternate stack of lanthanum oxide (La3+O2-) and iron pnictide (Fe2+P3-) layers. Magnetic and electrical resistivity measurements verify the occurrence of the superconducting transition at ∼4 K.

Iron-Based Layered Superconductor: LaOFeP

The absence of simple examples of superconductivity adjoining itinerant-electron ferromagnetism in the phase diagram has for many years cast doubt on the validity of conventional models of magnetically mediated superconductivity. On closer examination, however, very few systems have been studied in the extreme conditions of purity, proximity to the ferromagnetic state and very low temperatures required to test the theory definitively. Here we report the observation of superconductivity on the border of ferromagnetism in a pure system, UGe2, which is known to be qualitatively similar to the classic d-electron ferromagnets. The superconductivity that we observe below 1 K, in a limited pressure range on the border of ferromagnetism, seems to arise from the same electrons that produce band magnetism. In this case, superconductivity is most naturally understood in terms of magnetic as opposed to lattice interactions, and by a spin-triplet rather than the spin-singlet pairing normally associated with nearly antiferromagnetic metals.

Superconductivity on the border of itinerant-electron ferromagnetism in UGe2

FOLLOWING the discovery of superconductivity at ∼30 K in La2−xBaxCuO4 (ref. 1), a large number of related compounds have been found that are superconducting at relatively high temperatures. The feature common to all of these materials is a layered crystal structure based on a perovskite template and containing planar networks of copper and oxygen. This raises the question of whether superconductivity can occur in layered perovskites that do not contain copper. To the best of our knowledge, no such material has been found to date, despite nearly a decade of searching. We describe here the discovery of superconductivity in Sr2RuO4, a layered perovskite isostructural with La2−xBaxCuO4 (Fig. 1). Our results demonstrate that the presence of copper is not a prerequisite for the existence of superconductivity in a layered perovskite. But the low value of the superconducting transition temperature (Tc = 0.93 K) points towards a special role for copper in the high-temperature superconductors.

Superconductivity in a layered perovskite without copper

We report detailed normal state measurements of the resistivity, magnetic susceptibility and specific heat of high-quality single crystals of Sr 2 RuO 4 , the only copper-free, layered perovskite superconductor ( T c ≈1 K). It is intriguing that despite its very strong anisotropy (the ratio of the interlayer to in-plane resistivity exceeds 500) arising from the essentially two-dimensional Fermi surface, the normal state properties are consistent with a universal description for a strongly correlated Fermi liquid. Therefore, Sr 2 RuO 4 serves as an ideal reference material for the investigation of the limits of applicability of Fermi liquid theory to other highly correlated layered compounds, including high- T c cuprates.

Two-Dimensional Fermi Liquid Behavior of the Superconductor Sr2RuO4

Phylogenetic analyses were conducted using complete nucleotide sequences of the D-loop in the mitochondrial genome of Mola specimens, collected mainly in Japanese waters, to clarify the genetic features and distribution patterns of Mola sunfishes. Two significantly distinct groups (designated A and B) were present in the genus, with a considerable net nucleotide sequence divergence between the two (8.4%). The two groups occurred sympatrically around the Japanese coast, as previously suggested by Sagara et al. (2005). Group A occurred mostly on the Pacific coast of eastern Japan, while group B was widely distributed along the Kuroshio Current, strongly suggesting different migration routes for each group. The morphological characteristics of the two group specimens were differentiated via the head bump, body proportions and shape of the clavus. Through the addition of Mola sequence data taken from outside Japan to our phylogenetic analyses, three independent groups, including groups A and B, were found, each with a wide geographical distribution, which suggests the presence of at least three independent species within the genus Mola.

Phylogenetic relationship of two Mola sunfishes (Tetraodontiformes: Molidae) occurring around the coast of Japan, with notes on their geographical distribution and morphological characteristics

We investigated the territoriality and the spatial and mating relationships of the haremic hawkfish, Cirrhitichthys falco, on a reef off Kuchierabu-jima Island in southern Japan. Each individual maintained a territorial home range which was defended against same-sex conspecifics at the boundary of the home range. The territory of each male encompassed the territories of 2–3 females, allowing the male to completely monopolize mating opportunities with those females. Based on our observations, we classified the harem type of C. falco as a territorial female type. Large juveniles maintained independent home ranges outside the female territories. In contrast, small juveniles were allowed to cohabit within the territory of an adult female. Stomach contents analysis revealed that the smallest size class of C. falco fed primarily on copepods. In contrast, all other size classes fed primarily on decapods. Together, these results suggest that female territoriality plays an important role in defending food resources.

Harem structure and female territoriality in the dwarf hawkfish Cirrhitichthys falco (Cirrhitidae)

The community structure of copepods and chaetognaths in a Kuroshio-associated coastal area in the south of Japan was investigated in order to consider what forces (biological and/or physical) potentially produce drift zooplankton patches, an essential prey resource of planktivorous reef fish at the study site. On the basis of bimonthly samples of the patches and routine collections from October 1987 to August 1988, we compared the con~munity structures within and outside the patches. The patches consisted largely of a great variety of copepods and chaetognaths and exhibited high prey densities compared with routine samples. Within months, similarity values between patches and routine samples were relatively low, as were those between patches and the cumulative routme samples. In contrast, similarity values of patches compared with one another within months were high, as were those among months, suggesting that the patches depended on a common water mass retained through the entire year. Useful indicator species of the Kuroshio water and oceanic species dominated the patches in percentages and species numbers, while neritic species dominated routine samples. The neritic species composition of the patches was characterized by only 2 copepod species, Oncaea media and Microsetella norvegica, whereas the routine samples were numerically balanced by various neritic species. These results show that the zooplankton community structure in the patches is dominated by species which are usually found in the Kuroshio front formed in open sea environments. It may play an important role in supplying reef-dwelling planktivores with their main prey resource.

/pdf/enrichment-of-coastal-zooplankton-communities-by-drifting-4ezi4kozlz.pdf

Hiroaki Hashimoto

Papers

Superconductivity in a layered perovskite without copper

Two-Dimensional Fermi Liquid Behavior of the Superconductor Sr2RuO4

Phylogenetic relationship of two Mola sunfishes (Tetraodontiformes: Molidae) occurring around the coast of Japan, with notes on their geographical distribution and morphological characteristics

Harem structure and female territoriality in the dwarf hawkfish Cirrhitichthys falco (Cirrhitidae)

Enrichment of coastal zooplankton communities by drifting zooplankton patches from the Kuroshio front