Development of magnetic order in the TbNi(Al,In) series and magnetocrystalline anisotropy in TbTX compounds

9 páginas, 9 figuras, 4 tablas.-- PACS number(s): 71.20.Lp, 75.25.−j, 75.30.GwWe report on the magnetic structures in the TbNiAl1−xInx compounds as determined by powder neutron diffraction. These compounds belong to a large family of ternary rare-earth intermetallics crystallizing in the ZrNiAl-type hexagonal structure. All studied compounds order magnetically with magnetic structures characterized by k1=(0,0,0) and k2=(1/2,0,1/2) propagation vectors and magnetic moments aligned along or perpendicular to the hexagonal c axis. The magnetocrystalline anisotropy changes from uniaxial in the In-poor compounds (x≤0.4) to planar in the In-rich compounds (x≥0.5). The change of magnetocrystalline anisotropy type is a consequence of the development of structural parameters in the studied series. The Tb moments are oriented along the c axis when the nearest Tb-Tb distances between the planes are large compared to those within the planes, whereas Tb moments lie within the basal planes in the opposite case. This picture relating the structural parameters and anisotropy type can be generalized to the whole group of Tb-based compounds with the ZrNiAl type of structure.This work is a part of Research Project No. LG11024 financed by the Ministry of Education of the Czech Republic. The work was also supported by the Czech Science Foundation under Grant No. 202/09/1027. The work of M.K. was supported by Grant No. SVV-2011-263303.Peer reviewe

Macroscopic and microscopic study of a CePdIn compound

The magnetization and electrical resistivity measurements on a CePdIn single crystal as well as its preparation and structural characterization are presented. The negative paramagnetic Curie temperatures indicate antiferromagnetic ground state, the anisotropy of the paramagnetic Curie temperature amounts 22.7 K. No ferromagnetic correlations were indicated. Powder neutron diffraction experiment performed at temperatures down to 0.4 K did not lead to observation of any magnetic peak in diffraction patterns. We estimate the magnetic moment on Ce atoms to be significantly lower than 0.5-B. The temperature development of lattice parameters documents the standard thermal expansion of the unit cell; no signs of structural phase transition were observed

Achievement and Integration of Students with Special Needs (SEN) in the Fifth Grade

In Styria 77.3% of all students with special needs are educated in integrated classrooms. Currently, it is not known much either about the school performance nor the active class participation of these students. This study examined 230 fifth grade students – 43 with and 187 students without special educational needs (SEN). Moreover, it is important to acknowledge that the available data for this study represents the first wave of larger longitudinal study. The school performance of the students with SEN ranged one standard deviation below the level of the students without SEN. All students felt emotionally well integrated in the school settings, but the differences in the degree of social integration were evident. In fact, the students with SEN mentioned that they got along well with their classmates less frequently than the students without SEN

Neutron scattering study of the Tm2 Ir2 O7 pyrochlore iridate

The newly synthesized Tm2 Ir2 O7 iridate is investigated using neutron scattering techniques. Powder neutron diffraction patterns confirm that Tm2 Ir2 O7 crystallizes in a cubic structure of pyrochlore type, consistent with the rest of the rare-earth A2 Ir2 O7 series, and the crystal structure is preserved down to 0.2 K. The thermal expansion of the crystal lattice is well described by a Debye model of lattice vibrations. A weak magnetic signal consistent with the so-called all-in-all-out magnetic order (AIAO) is traced at low temperature; however, it cannot serve as unambiguous evidence of the AIAO structure in the compound. Nondispersive magnetic excitations in energy-momentum space are observed in inelastic neutron scattering spectra of Tm2 Ir2 O7. The crystal-field scheme and parameters of the thulium iridate are refined and discussed with respect to the specific heat and magnetization data. The results are supported by mean-field calculations

Linking Self-Rated Social Inclusion to Social Behaviour. An Emperical Study of Students with and without Special Education in Secondary Schools

Successful inclusive education creates a learning environment that supports not only the cognitive abilities of all children but also their social and emotional development. The present study focuses on the development of social participation of students with and without special education needs (SEN). A longitudinal study with two measurement times was conducted. The first measurement (T1) took place at the end of fifth grade, the second (T2) one year later. The sample consisted of 35 SEN students and108 non-SEN students from mainstream classes in Graz, Austria. For assessing the self-perception of social inclusion, items from the ‘dimensions of integration’ questionnaire (FDI 4–6) were used. Social participation does not seem to be a very stable phenomenon; its retest reliability was only .47 for SEN students and .54 for non-SEN students. Results indicate that children with SEN experienced less social participation than children without SEN at T1 and T2. To identify the predictors for social participation, a multiple regression analysis was conducted. Next to social participation at T1, indirect aggressive behaviour (self-assessed) also appears to predict social participation at T2

Magnetic structures and excitations in CePd2(Al, Ga)2 series: Development of the "vibron" states

CePd2Al2-xGax compounds crystallizing in the tetragonal CaBe2Ge2-type structure (space group P4/nmm) and undergoing a structural phase transition to an orthorhombic structure (Cmme) at low temperatures were studied by means of neutron scattering. The amplitude-modulated magnetic structure of CePd2Al2 is described by an incommensurate propagation vector k - =(dx, 12+dy, 0) with dx=0.06 and dy=0.04. The magnetic moments order antiferromagnetically within the ab planes stacked along the c axis and are arranged along the direction close to the orthorhombic a axis with a maximum value of 1.5(1) µB/Ce3+. CePd2Ga2 reveals a magnetic structure composed of two components: the first is described by the propagation vector k1 - =(12, 12, 0), and the second one propagates with k2 - =(0, 12, 0). The magnetic moments of both components are aligned along the same direction - the orthorhombic 100] direction - and their total amplitude varies depending on the mutual phase of magnetic moment components on each Ce site. The propagation vectors k1 - and k2 - describe also the magnetic structure of substituted CePd2Al2-xGax compounds, except the one with x=0.1.CePd2Al1.9Ga0.1 with magnetic structure described by k - and k1 - stays on the border between pure CePd2Al2 and the rest of the series. Determined magnetic structures are compared with other Ce 112 compounds. Inelastic neutron scattering experiments disclosed three nondispersive magnetic excitations in the paramagnetic state of CePd2Al2, while only two crystal field (CF) excitations are expected from the splitting of ground state J=52 of the Ce3+ ion in a tetragonal/orthorhombic point symmetry. Three magnetic excitations at 1.4, 7.8, and 15.9 meV are observed in the tetragonal phase of CePd2Al2. A structural phase transition to an orthorhombic structure shifts the first excitation up to 3.7 meV, while the other two excitations remain at almost the same energy. The presence of an additional magnetic peak is discussed and described within the Thalmeier-Fulde CF-phonon coupling (i.e., magnetoelastic coupling) model generalized to the tetragonal point symmetry. The second parent compound CePd2Ga2 does not display any sign of additional magnetic excitation. The expected two CF excitations were observed. The development of magnetic excitations in the CePd2Al2-xGax series is discussed and crystal field parameters determined

Effects of Cooperative Learning Methods in German Language Arts on Reading Ability and Social Behavior of High School Students

This study examined the implementation and outcomes of cooperative learning methods in daily school life. In the context of an intervention wait-list control group research design lasting over two years, a group of Austrian students was taught using mainly cooperative learning methods in German language arts. In addition to standardized tests, self and peer report questionnaires assessed reading ability and aspects of social behavior before and after the intervention. Focus group interviews of teachers were used to investigate the implementation of cooperative learning methods in daily class life. The participants were nineteen teachers and 294 fifth and sixth graders from eight different schools at the secondary level. The results show that teachers prefer relatively specific cooperative learning methods. The results also illustrate that students who used cooperative learning methods in German language classes developed significantly better in reading comprehension than the students in the wait-list control group. However, concerning the reports of social behavior, most differences between the two groups failed to reach statistical significance

New type of magnetic structure in the R2T2X group Tb2Pd2In

Anisotropy of bulk magnetic properties and magnetic structure studies of a Tb2Pd2In single crystal by means of bulk magnetization methods and neutron diffraction techniques confirmed the antiferromagnetic order below the N el temperature 29.5 K. The collinear magnetic structure of Tb magnetic moments aligned along the tetragonal c axis is characterized by a propagation vector k 1 4, 1 4, 1 2 , yielding an equal moment structure with alternating coupling between nearest as well as next nearest Tb neighbors within the basal plane and antiferromagnetic coupling between the c axis neighbors. In the context of magnetism of R2T2X compounds, where R stands for rare earth or actinide element, such collinear structure with long wavelength periodicity represents a new type of magnetic structure

Teaching and learning in a multilingual Europe: findings from a cross-European study

School classrooms within the EU are multilingual learning environments. The diversity of pupils in classrooms raises significant challenges for teachers, but to date, there are no data from large-scale surveys that compare views within and across European countries. A bespoke questionnaire was designed to examine views of current classroom learning environments with respect to the multilingualism. The questionnaire was piloted and subsequently completed by 2792 teachers across different European countries. Eleven countries provided sufficient data for analyses. Results from structural equation modelling showed that teachers’ attitudes could be reliably measured across Europe with the use of carefully devised questionnaire, whose loading and factor structure remained invariant across countries. Teachers’ views about multilingualism were most challenged by the numbers of children in their classes, not the percentage of multilingual pupils in the class. Countries differed in how they perceived multilingualism, with their differences leading to distinctive country clusters. Gender and education level (elementary vs. secondary) differences were also observed irrespective of country. These findings enhance our understanding of the role that the characteristics of teachers and their classrooms play in a multilingual setting across diverse European settings. The practical relevance of the results and new opportunities for teacher training are discussed