Chemically induced ferromagnetism near room temperature in single crystal (Zn1-x Cr x )Te half-metal.

Magnetic semiconductors are at the core of recent spintronics research endeavors. Chemically doped II-VI diluted magnetic semiconductors, such as (Zn1-x Cr x )Te, provide a promising platform in this quest. However, a detailed knowledge of the microscopic nature of magnetic ground state is necessary for any practical application. Here, we report on the synergistic study of (Zn1-x Cr x )Te single crystals using elastic neutron scattering measurements and density functional calculations. For the first time, our research unveils the intrinsic properties of ferromagnetic state in a macroscopic specimen of (Zn0.8Cr0.2)Te. The ferromagnetism is onset at T C ∼ 290 K and remains somewhat independent to modest change in the substitution coefficient x. We show that magnetic moments on Zn/Cr sites develop ferromagnetic correlation in the a-c plane with a large ordered moment of µ = 3.08 µ B. Magnetic moment across the lattice is induced via the mediation of Te sites, uncoupled to the number of dopant carriers as inferred from the density functional calculation. Additionally, the ab initio calculations also reveal half-metallicity in x = 0.2 composition. These properties are highly desirable for future spintronic applications.

Magnetic crystalline-symmetry-protected axion electrodynamics and field-tunable unpinned Dirac cones in EuIn2As2.

Knowledge of magnetic symmetry is vital for exploiting nontrivial surface states of magnetic topological materials. EuIn2As2 is an excellent example, as it is predicted to have collinear antiferromagnetic order where the magnetic moment direction determines either a topological-crystalline-insulator phase supporting axion electrodynamics or a higher-order-topological-insulator phase with chiral hinge states. Here, we use neutron diffraction, symmetry analysis, and density functional theory results to demonstrate that EuIn2As2 actually exhibits low-symmetry helical antiferromagnetic order which makes it a stoichiometric magnetic topological-crystalline axion insulator protected by the combination of a 180∘ rotation and time-reversal symmetries: [Formula: see text]. Surfaces protected by [Formula: see text] are expected to have an exotic gapless Dirac cone which is unpinned to specific crystal momenta. All other surfaces have gapped Dirac cones and exhibit half-integer quantum anomalous Hall conductivity. We predict that the direction of a modest applied magnetic field of µ0H ≈ 1 to 2 T can tune between gapless and gapped surface states.

Spin reorientation in antiferromagnetic Dy2FeCoO6 double perovskite.

We explored the electronic and magnetic properties of the lanthanide double perovskite Dy2FeCoO6 by combining magnetization, Raman and Mössbauer spectroscopy and neutron diffraction along with density functional theory (DFT) calculations. Our magnetization measurements revealed two magnetic phase transitions in Dy2FeCoO6. First, a paramagnetic to antiferromagnetic transition at T N = 248 K and subsequently, a spin reorientation transition at T SR = 86 K. In addition, a field-induced magnetic phase transition with a critical field of H c ≈ 20 kOe is seen at 2 K. Neutron diffraction data suggested cation-disordered orthorhombic structure for Dy2FeCoO6 in Pnma space group which is supported by Raman scattering results. The magnetic structures ascertained through representational analysis indicate that at T N, a paramagnetic state is transformed to Γ5(Cx, Fy, Az) antiferromagnetic structure while, at T SR, Fe/Co moments undergo a spin reorientation to Γ3(Gx, Ay, Fz). The refined magnetic moment of (Fe/Co) is 1.47(4) µ B at 7 K. The antiferromagnetic structure found experimentally is supported through the DFT calculations which predict an insulating electronic state in Dy2FeCoO6.

Collinear antiferromagnetism in trigonal SrMn2As2 revealed by single-crystal neutron diffraction.

Iron pnictides and related materials have been a topic of intense research for understanding the complex interplay between magnetism and superconductivity. Here we report on the magnetic structure of SrMn2As2 that crystallizes in a trigonal structure ([Formula: see text]) and undergoes an antiferromagnetic (AFM) transition at [Formula: see text] K. The magnetic susceptibility remains nearly constant at temperatures [Formula: see text] with [Formula: see text] whereas it decreases significantly with [Formula: see text]. This shows that the ordered Mn moments lie in the [Formula: see text] plane instead of aligning along the [Formula: see text]-axis as in tetragonal BaMn2As2. Single-crystal neutron diffraction measurements on SrMn2As2 demonstrate that the Mn moments are ordered in a collinear Néel AFM phase with [Formula: see text] AFM alignment between a moment and all nearest neighbor moments in the basal plane and also perpendicular to it. Moreover, quasi-two-dimensional AFM order is manifested in SrMn2As2 as evident from the temperature dependence of the order parameter.

Magnetic fluctuations driven insulator-to-metal transition in Ca(Ir(1-x)Rux)O3.

Magnetic fluctuations in transition metal oxides are a subject of intensive research because of the key role they are expected to play in the transition from the Mott insulator to the unconventional metallic phase of these materials, and also as drivers of superconductivity. Despite much effort, a clear link between magnetic fluctuations and the insulator-to-metal transition has not yet been established. Here we report the discovery of a compelling link between magnetic fluctuations and the insulator-to-metal transition in Ca(Ir1-xRux)O3 perovskites as a function of the substitution coefficient x. We show that when the material turns from insulator to metal, at a critical value of x ~ 0.3, magnetic fluctuations tend to change their character from antiferromagnetic, a Mott insulator phase, to ferromagnetic, an itinerant electron state with Hund's orbital coupling. These results are expected to have wide-ranging implications for our understanding of the unconventional properties of strongly correlated electrons systems.

[Current status of total hip and knee replacements in Germany - results of a nation-wide survey]. / Aktueller Status der Hüft- und Knieendoprothetik in Deutschland - Ergebnisse einer bundesweiten Umfrage.

BACKGROUND: Total hip and knee replacements are very frequently performed operative procedures in German hospitals. Despite the high number of cases, only few data on treatment procedures of the clinical routine and their impact on postoperative length of stay and clinical outcome are available. The aim of our survey was to gain detailed insights of the treatment procedures in patients scheduled for elective hip or knee replacement in order to extract recommendations for improving patient care. METHODS: In a nation-wide survey, we asked leading physicians of 694 trauma surgery and orthopaedic surgery departments and their corresponding colleagues in the departments of anaesthesia for treatment procedures including the process of patient admission, surgical techniques, postoperative analgesia, discharge management and follow-up. We used a multiple linear regression for analysing variables impacting on the postoperative length of stay. RESULTS: Altogether, 303 replies representing 31.8 % of the contacted hospitals could be evaluated. For hip arthroplasty, the anterolateral approach was most commonly chosen. For knee arthroplasty, the parapatellar approach was most frequently used. Tourniquet and wound drainage (mostly removed on the second postoperative day) were widely used with more than 90 %. The avoidance of wound drainage was associated with a lower postoperative length of stay for patients following total hip or knee replacement. Only 70 % of the German departments followed up their patients after discharge checking especially the range of motion of the artificial joint replacement. CONCLUSION: The treatment procedures for elective hip and knee replacement are very heterogeneous in German hospitals. The quality of the clinical outcome cannot be related to a single procedure; in fact the choice and complementary interaction of interventions are essential for improving patient care. These results provide first important evidence to which extent organisational structures and treatment procedures affect patient care and length of stay. Therefore, the analyses show relevant indications for an optimised standard in patient care.

Effects of transition metal substitutions on the incommensurability and spin fluctuations in BaFe2As2 by elastic and inelastic neutron scattering.

The spin fluctuation spectra from nonsuperconducting Cu-substituted, and superconducting Co-substituted, BaFe(2)As(2) are compared quantitatively by inelastic neutron scattering measurements and are found to be indistinguishable. Whereas diffraction studies show the appearance of incommensurate spin-density wave order in Co and Ni substituted samples, the magnetic phase diagram for Cu substitution does not display incommensurate order, demonstrating that simple electron counting based on rigid-band concepts is invalid. These results, supported by theoretical calculations, suggest that substitutional impurity effects in the Fe plane play a significant role in controlling magnetism and the appearance of superconductivity, with Cu distinguished by enhanced impurity scattering and split-band behavior.

Ba(1-x)K(x)Mn2As2: an antiferromagnetic local-moment metal.

The compound BaMn2As2 with the tetragonal ThCr2Si2 structure is a local-moment antiferromagnetic insulator with a Néel temperature T(N)=625 K and a large ordered moment µ=3.9µ(B)/Mn. We demonstrate that this compound can be driven metallic by partial substitution of Ba by K while retaining the same crystal and antiferromagnetic structures together with nearly the same high T(N) and large µ. Ba(1-x)K(x)Mn2As2 is thus the first metallic ThCr2Si2-type MAs-based system containing local 3d transition metal M magnetic moments, with consequences for the ongoing debate about the local-moment versus itinerant pictures of the FeAs-based superconductors and parent compounds. The Ba(1-x)K(x)Mn2As2 class of compounds also forms a bridge between the layered iron pnictides and cuprates and may be useful to test theories of high T(c) superconductivity.

Picovoltmeter for probing vortex dynamics in a single weak-pinning Corbino channel.

We have developed a picovoltmeter using a Nb dc superconducting quantum interference device for measuring the flux-flow voltage from a small number of vortices moving through a submicron weak-pinning superconducting channel. We have applied this picovoltmeter to measure the vortex response in a single channel arranged in a circle on a Corbino disk geometry. The circular channel allows the vortices to follow closed orbits without encountering any sample edges, thus eliminating the influence of entry barriers.

Stiffness, elastic limit, and strength of newer types of endodontic posts.

OBJECTIVES: To determine the stiffness, elastic limit, and strength of a selection of endodontic posts recently introduced onto the market. METHODS: Endodontic posts of zirconia (Biopost, Cerapost), titanium (PCR), and carbon fiber (Composipost) were cemented in a brass block and loaded at an angle of 45 degrees in an Instron Testing Machine. From the recorded relationship between force and deflection the three mechanical properties were determined (n = 10 in each group). RESULTS: The ceramic posts were very stiff and strong, with no plastic behavior. The PCR post was as strong as, but less stiff than, the ceramic posts. Composipost had the lowest values for stiffness, elastic limit, and strength of the posts investigated. CONCLUSION: The posts under investigation differed significantly with respect to mechanical properties.

Direct pulp capping with a dentinal adhesive resin system: a pilot study.

The clinical and histological responses of exposed pulpal tissue after direct capping appear to be more closely related to bacterial infiltration than to direct material toxicity. Dentinal bonding agents have been suggested as a replacement for calcium hydroxide for pulpal protection. In this pilot study, direct pulp capping with a glutaraldehyde-containing dentinal adhesive was performed on eight permanent premolars and molars. The teeth were immediately restored with a resin composite restoration. The clinical technique included the use of a calcium hydroxide paste to cover the exposure site during completion of the preparation. Enamel and dentin were etched with phosphoric acid. All teeth remained vital and without symptoms during the initial observation period of 2 to 6 months.

Root canals in one-rooted maxillary second molars.

The Royal Dental College, Copenhagen, houses an extensive collection of human teeth extracted in Denmark. The collection currently contains 104 one-rooted, permanent maxillary second molars. The root complex on these teeth was sectioned at the junction between the coronal and the apical halves, i.e. mid-root, and at the junction between the middle and the apical thirds, i.e. apically. Using a stereomicroscope we then registered, mid-root and apically, the following variables: canal number, canal position, and canal cross-section. Mid-root there was 1 centrally located root canal in 25.96% of the teeth examined; 2 canals were observed either mesially and distofacially, mesiofacially and distally, or facially and lingually in 34.62%; 3 canals positioned mesiofacially, distofacially, and lingually were found in 39.42%. At the same level 63.51% of the canal cross-sections were non-circular, whereas 36.49% of the canals had a circular cross-section image. The non-circular canal cross-sections could more specifically be characterized as C-shaped, Y-shaped, hourglass-shaped or the root canal had a greater faciolingual than mesiodistal extension or, respectively, a greater mesiodistal than faciolingual extension. Apically there was 1 centrally located root canal in 35.58%; 2 canals were observed with a position either mesially and distofacially, mesiofacially and distally, or facially and lingually in 37.49%; 3 canals located mesiofacially, distofacially, and lingually were found in 26.92%. At the apical level, 64.32% of the root canal cross-sections were non-circular, whereas 35.68% of the canals showed a circular cross-section. The results presented here are aimed at: clinical dentists, endodontists, and dental morphologists.

Effects of hexachlorobenzene and iron loading on rat liver mitochondria.

The effects of hexachlorobenzene treatment and simultaneous iron-overload on the iron and porphyrin content of rat liver and rat liver mitochondria have been examined. In order to assess damages to the mitochondrial membrane occurring with these treatments, the content of malondialdehyde and selected functional properties of mitochondria were compared with those from control animals. Prolonged intake of hexachlorobenzene (8 weeks) resulted in a strikingly increased level of porphyrins together with a moderate increase in iron concentration. Simultaneous administration of hexachlorobenzene and iron-dextran caused the porphyrin level to reach 25% of the amount induced by hexachlorobenzene alone. The iron concentrations in liver as well as in liver mitochondria are also decreased under these conditions, as compared to the effect of iron-dextran. In contrast, the effects of hexachlorobenzene combined with iron-dextran on mitochondrial oxidative phosphorylation and malondialdehyde content are greater than those of either hexachlorobenzene or iron-dextran. These data suggest that porphyrin accumulation per se causes little deleterious effect and that both agents administered together act synergistically in causing damage to the mitochondrial membrane.