Carrier-induced ferromagnetism in n-type ZnMnAlO and ZnCoAlO thin films at room temperature

The realization of semiconductors that are ferromagnetic above room temperature will potentially lead to a new generation of spintronic devices with revolutionary electrical and optical properties. Transition temperatures in doped ZnO are high but, particularly for Mn doping, the reported moments have been small. We show that by careful control of both oxygen deficiency and aluminium doping the ferromagnetic moments measured at room temperature in n-type ZnMnO and ZnCoO are close to the ideal values of 5mB and 3mB respectively. Furthermore a clear correlation between the magnetisation per transition metal ion and the ratio of the number of carriers to the number of transition metal donors was established as is expected for carrier induced ferromagnetism for both the Mn and Co doped films. The dependence of the magnetisation on carrier density is similar to that predicted for the transition temperature for a dilute magnetic semiconductor in which the exchange between the transition metal ions is through the free carriers.Comment: 14 pages pd

Spin polarized transport current in n-type co-doped ZnO thin films measured by Andreev spectroscopy

We use point contact Andreev reflection measurements to determine the spin polarization of the transport current in pulse laser deposited thin films of ZnO with 1% Al and with and without 2%Mn. Only films with Mn are ferromagnetic and show spin polarization of the transport current of up to 55 $\pm$ 0.5% at 4.2 K, in sharp contrast to measurements of the nonmagnetic films without Mn where the polarization is consistent with zero. Our results imply strongly that ferromagnetism in these Al doped ZnO films requires the presence of Mn.Comment: Published versio

Room temperature magneto-optics of ferromagnetic transition-metal doped ZnO thin films

Magneto-optic studies of ZnO doped with transition metals Co, Mn, V and Ti indicate a significant magnetic circular dichroism (MCD) at the ZnO band edge at room temperature, together with an associated dispersive Faraday rotation. Similar spectra occur for each dopant which implies that the ferromagnetism is an intrinsic property of the bulk ZnO lattice. At 10 K additional paramagnetic contributions to the MCD are observed, but above about 150K, the magnitude of the MCD signal is dominated by the ferromagnetism and is almost temperature independent. The MCD at the ZnO band edge shows room temperature hysteretic behaviour.Comment: 4 page

Investigating the State of Play of Geobim Across Europe

In both the Geographic Information (Geo) and Building Information Modelling (BIM) domains, it is widely acknowledged that the integration of data from both domains is beneficial and a crucial step in facing the multi-disciplinary challenges of our built environment. The result of this integration – which can broadly be termed GeoBIM – could answer questions such as identifying an appropriate Heating, Ventilation and Air Conditioning system for a building based on room usage, outside air temperature, solar exposure and traffic pollution or validating whether a proposed built asset meets relevant planning constraints. Developing a coherent approach to GeoBIM integration requires consensus between multiple stakeholders from both the Geo and the BIM side and at an international level. This multi-country and multi-stakeholder approach is the topic of a 2-year EuroSDR project on GeoBIM integration that started in November 2017. The general aim of the project is to detail both the needs and the issues of GeoBIM integration, studied from use cases as well as from existing experiences in the participating countries and to develop initial solutions accordingly. This paper reports initial results – it identifies strong potential for GeoBIM but also rather fragmented activity, with no national level focus. It also notes that research (both in industry and academia) primarily focuses on standards, interoperability and data integration or exchange. Based on these findings – and with a focus on existing work and topics of interest to NMCAs – the next phase of the work will develop more detailed case studies for Asset Management and Urban Planning

On the feasibility of N2 fixation via a single-site FeI/FeIV cycle: Spectroscopic studies of FeI(N2)FeI, FeIV=N, and related species

The electronic properties of an unusually redox-rich iron system, [PhBPR 3]FeNx (where [PhBPR 3] is [PhB(CH2PR2)3]−), are explored by Mössbauer, EPR, magnetization, and density-functional methods to gain a detailed picture regarding their oxidation states and electronic structures. The complexes of primary interest in this article are the two terminal iron(IV) nitride species, [PhBPiPr 3]FeN (3a) and [PhBPCH2Cy 3]FeN (3b), and the formally diiron(I) bridged-Fe(μ-N2)Fe species, {[PhBPiPr 3]Fe}2(μ-N2) (4). Complex 4 is chemically related to 3a via a spontaneous nitride coupling reaction. The diamagnetic iron(IV) nitrides 3a and 3b exhibit unique electronic environments that are reflected in their unusual Mössbauer parameters, including quadrupole-splitting values of 6.01(1) mm/s and isomer shift values of −0.34(1) mm/s. The data for 4 suggest that this complex can be described by a weak ferromagnetic interaction (J/D < 1) between two iron(I) centers. For comparison, four other relevant complexes also are characterized: a diamagnetic iron(IV) trihydride [PhBPiPr 3]Fe(H)3(PMe3) (5), an S = 3/2 iron(I) phosphine adduct [PhBPiPr 3]FePMe3 (6), and the S = 2 iron(II) precursors to 3a, [PhBPiPr 3]FeCl and [PhBPiPr 3]Fe-2,3:5,6-dibenzo-7-aza bicyclo[2.2.1]hepta-2,5-diene (dbabh). The electronic properties of these respective complexes also have been explored by density-functional methods to help corroborate our spectral assignments and to probe their electronic structures further

An oribatid mite (Arachnida: Acari) from the Oxford Clay (Jurassic: Upper Callovian) of South Cave Station Quarry, Yorkshire, UK

A single specimen of a new species of oribatid mite belonging to the genus Jureremus Krivolutsky, in Krivolutsky and Krassilov 1977, previously described from the Upper Jurassic of the Russian Far East, is described as J. phippsi sp. nov. The mite is preserved by iron pyrite replacement, and was recovered by sieving from the Oxford Clay Formation (Jurassic: Upper Callovian) of South Cave, Yorkshire. It is the first record of a pre-Pleistocene mite, and the second species record of the family Cymbaeremaeidae, from the British Isles; also, it is only the third record of Acari from the Jurassic Period. The presence of a terrestrial mite in a sedimentary sequence of open marine origin is noteworthy, and suggestions for its mode of transport to the site of deposition are discussed

Tropical Herbivorous Phasmids, but Not Litter Snails, Alter Decomposition Rates By Modifying Litter Bacteria

Consumers can alter decomposition rates through both feces and selective feeding in many ecosystems, but these combined effects have seldom been examined in tropical ecosystems. Members of the detrital food web (litter-feeders or microbivores) should presumably have greater effects on decomposition than herbivores, members of the green food web. Using litterbag experiments within a field enclosure experiment, we determined the relative effects of common litter snails (Megalomastoma croceum) and herbivorous walking sticks (Lamponius portoricensis) on litter composition, decomposition rates, and microbes in a Puerto Rican rainforest, and whether consumer effects were altered by canopy cover presence. Although canopy presence did not alter consumers’ effects, focal organisms had unexpected influences on decomposition. Decomposition was not altered by litter snails, but herbivorous walking sticks reduced leaf decomposition by about 50% through reductions in high quality litter abundance and, consequently, lower bacterial richness and abundance. This relatively unexplored but potentially important link between tropical herbivores, detritus, and litter microbes in this forest demonstrates the need to consider autotrophic influences when examining rainforest ecosystem processes