Thickness-dependent magnetic structure of ultrathin Fe/Ir(001) films: from spin-spiral states towards ferromagnetic order

We present a detailed study of the ground-state magnetic structure of ultrathin Fe films on the surface of fcc Ir(001). We use the spin-cluster expansion technique in combination with the relativistic disordered local moment scheme to obtain parameters of spin models and then determine the favored magnetic structure of the system by means of a mean field approach and atomistic spin dynamics simulations. For the case of a single monolayer of Fe we find that layer relaxations very strongly influence the ground-state spin configurations, whereas Dzyaloshinskii-Moriya (DM) interactions and biquadratic couplings also have remarkable effects. To characterize the latter effect we introduce and analyze spin collinearity maps of the system. While for two monolayers of Fe we find a single-q spin spiral as ground state due to DM interactions, for the case of four monolayers the system shows a noncollinear spin structure with nonzero net magnetization. These findings are consistent with experimental measurements indicating ferromagnetic order in films of four monolayers and thicker.Comment: 9 pages, 7 figure

Spin-correlations and magnetic structure in an Fe monolayer on 5d transition metal surfaces

We present a detailed first principles study on the magnetic structure of an Fe monolayer on different surfaces of 5d transition metals. We use the spin-cluster expansion technique to obtain parameters of a spin model, and predict the possible magnetic ground state of the studied systems by employing the mean field approach and in certain cases by spin dynamics calculations. We point out that the number of shells considered for the isotropic exchange interactions plays a crucial role in the determination of the magnetic ground state. In the case of Ta substrate we demonstrate that the out-of-plane relaxation of the Fe monolayer causes a transition from ferromagnetic to antiferromagnetic ground state. We examine the relative magnitude of nearest neighbour Dzyaloshinskii-Moriya (D) and isotropic (J) exchange interactions in order to get insight into the nature of magnetic pattern formations. For the Fe/Os(0001) system we calculate a very large D/J ratio, correspondingly, a spin spiral ground state. We find that, mainly through the leading isotropic exchange and Dzyaloshinskii-Moriya interactions, the inward layer relaxation substantially influences the magnetic ordering of the Fe monolayer. For the Fe/Re(0001) system characterized by large antiferromagnetic interactions we also determine the chirality of the $120^{\circ}$ N\'eel-type ground state.Comment: 15 pages, 8 figures, 2 table

Metallic magnetism at finite temperatures studied by relativistic disordered moment description: Theory and applications

We develop a self-consistent relativistic disordered local moment (RDLM) scheme aimed at describing finite temperature magnetism of itinerant metals from first principles. Our implementation in terms of the Korringa--Kohn--Rostoker multiple scattering theory and the coherent potential approximation allows to relate the orientational distribution of the spins to the electronic structure, thus a self-consistent treatment of the distribution is possible. We present applications for bulk bcc Fe, L1$_0$-FePt and FeRh ordered in the CsCl structure. The calculations for Fe show significant variation of the local moments with temperature, whereas according to the mean field treatment of the spin fluctuations the Curie temperature is overestimated. The magnetic anisotropy of FePt alloys is found to depend strongly on intermixing between nominally Fe and Pt layers, and it shows a power-law behavior as a function of magnetization for a broad range of chemical disorder. In case of FeRh we construct a lattice constant vs. temperature phase diagram and determine the phaseline of metamagnetic transitions based on self-consistent RDLM free energy curves.Comment: 11 pages, 8 figure

PLOTREP: a web tool for defragmentation and visual analysis of dispersed genomic repeats

Identification of dispersed or interspersed repeats, most of which are derived from transposons, retrotransposons or retrovirus-like elements, is an important step in genome annotation. Software tools that compare genomic sequences with precompiled repeat reference libraries using sensitive similarity-based methods provide reliable means of finding the positions of fragments homologous to known repeats. However, their output is often incomplete and fragmented owing to the mutations (nucleotide substitutions, deletions or insertions) that can result in considerable divergence from the reference sequence. Merging these fragments to identify the whole region that represents an ancient copy of a mobile element is challenging, particularly if the element is large and suffered multiple deletions or insertions. Here we report PLOTREP, a tool designed to post-process results obtained by sequence similarity search and merge fragments belonging to the same copy of a repeat. The software allows rapid visual inspection of the results using a dot-plot like graphical output. The web implementation of PLOTREP is available at

GINA - A Polarized Neutron Reflectometer at the Budapest Neutron Centre

The setup, capabilities and operation parameters of the neutron reflectometer GINA, the recently installed "Grazing Incidence Neutron Apparatus" at the Budapest Neutron Centre, are introduced. GINA, a dance-floor-type, constant-energy, angle-dispersive reflectometer is equipped with a 2D position-sensitive detector to study specular and off-specular scattering. Wavelength options between 3.2 and 5.7 {\AA} are available for unpolarized and polarized neutrons. Spin polarization and analysis are achieved by magnetized transmission supermirrors and radio-frequency adiabatic spin flippers. As a result of vertical focusing by the five-element (pyrolytic graphite) monochromator the reflected intensity from a 20x20 mm sample has doubled. GINA is dedicated to studies of magnetic films and heterostructures, but unpolarized options for non-magnetic films, membranes and other surfaces are also provided. Shortly after its startup, reflectivity values as low as 3x10-5 have been measured on the instrument. The facility is now open for the international user community, but its development is continuing mainly to establish new sample environment options, the spin analysis of off-specularly scattered radiation and further decrease of the background

A Balaton környéki kisvízfolyások makroszkópikus gerinctelen faunája | On the macroinvertebrate fauna of inflows of lake Balaton

A Balaton környéki kisvízfolyások makroszkópikus gerinctelen faunája kevéssé ismert. Habár számos faunisztikai jellegű gyűjtést végeztek ezen a területen, ezekben a publikációkban csak szórványos adatok találhatók. Dolgozatunkban átfogó irodalmi áttekintést adunk a Balaton környéki patakok makrogerinctelen faunájáról, illetve saját, 2006-ban végzett faunisztikai felmérésünk eredményeit mutatjuk be. | The aquatic macroinvertebrate fauna of streams in the catchment area of Lake Balaton is poorly known. Although there were carried out many faunistical investigation in this area, only sporadic data can be found in the literature. In this paper a compilation is given on the macroinvertebrate fauna of streams of Lake Balaton, and the results of own faunistical investigations carried out in 2006 are presented

Meat production and maintaining biodiversity: Grazing by traditional breeds and crossbred beef cattle in marshes and grasslands

Questions: Sustainable rangeland utilization considering traditions and economic reasons is compulsory for harmonising the needs of the agricultural and nature conservation sectors. For proper rangeland management it is crucial to compare the grazing effects of traditional breeds and crossbred animals of the same species that might have different effects on the rangelands. To fill this knowledge gap, in a grazing experiment, we investigated the effect of cattle breeds on the vegetation to test the effects on nature conservation value and agricultural production value. We hypothesized that the effects of cattle grazing on habitat conservation values and forage quality depend on the grazing breed, because breeds differ in selectivity, body size and trampling effect. Location: Marshes and alkaline wet grasslands in Hortobágy National Park, Hungary. Methods: We recorded the percentage cover of vascular plants in three consecutive years in a total of 60 plots in 12 areas grazed by traditional (0.61 AU/ha) and largesized crossbred beef cattle (0.68 AU/ha). Results: We found that the effect of cattle breed on the habitat conservation values and forage quality is dependent on the habitat type. The traditional breed maintained a significantly higher species number and Shannon diversity in marshes than the crossbred beef cattle. Grazing of crossbred cattle led to decreasing moisture indicator values in marsh habitats. Conclusions: Our findings revealed that traditional breeds should be prioritized in the management of wet alkaline grasslands and marshes. Crossbred beef cattle might be a substitute but only in case traditional breeds are not available for the management of alkaline wet grasslands. In marshes, however, we recommend prioritizing the traditional breeds as they maintain higher diversity compared to crossbred beef cattle

An improved method for embryogenic suspension cultures of 'Richter 110' rootstock

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Vergleich von artenreichen Begrünungsmischungen in ungarischen Weingebieten

Intensive mechanical soil cultivation and herbicide treatment was often the preferred technology in vineyards in the second half of the 20th century. In the last decades we increasingly experienced the disadvantages of these technologies: soil degradation, erosion and deflation damages. The use of well-adapted cover-crop mixtures could be an alternative. In 2012 we started to study three different species-rich cover crop mixtures (Biocont-Ecovin, Legume mixture, Grass-herb mixture) in Hungarian vineyards. For 2013 we detected lower weed coverage in the inter-rows sown with the Grass-herb and Legume mixtures, while in control and Biocont-Ecovin inter-rows we detected increasing weed coverage. In the third year (2014) we found in case of every plot that the grass-herb mixture-covered inter-rows were the least weedy. The most successful species in the inter-rows are: Coronilla varia, Lotus corniculatus, Medicago lupulina, Onobrychis viciifolia, Plantago lanceolata, Trifolium repens, Trifolium pratense