Magnetic ordering and charge transport in electron-doped La₁-yCeyMnO₃ (0.1 ≤ y ≤ 0.3) films

Microstructure, magnetic and transport properties of the as-deposited La₁−yCeyMnO₃(0.1 ≤ y ≤ 0.3) films, prepared by a pulse laser deposition, have been investigated in wide region of temperature and magnetic field. The microstructure analysis reveals that all films have a high c-oriented texture, the orthorhombic crystal lattice and the negligible quantity of CeO₂ inclusions. The observed strip-domain phase with a periodic spacing of about 3c, the crystal lattice of which is the same to the basic film phase, reveals the magnetic behavior typical for the Griffiths phase. The regions of the double-period modulated phase was found at room temperature in the y = 0.1 film, which are treated as the Mn³⁺/Mn²⁺ ordering with the partial ferromagnetic → antiferromagnetic transition at TN ≤ 80 K. At the same time, the carried out investigation manifests that the magnetic and transport properties of the electron-doped La₁-yCeyMnO₃ films, driven by a cation doping, are similar to that for the hole-doped La/Ca manganites. Therefore, one can conclude, that does not exist of a principle difference between the mechanisms of spin-ordering and charge-transport in the hole- and the electron-doped manganites

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Magnetic and transport properties of La₀.₇Sr₀.₃MnO₃/Pr₀.₆₅Ca₀.₃₅MnO₃ multilayered films with different microstructure

The magnetic and transport properties of single-crystal and polycrystalline La₀.₇Sr₀.₃MnO₃/Pr₀.₆₅Ca₀.₃₅MnO₃ multilayered films are investigated in the temperature range 4.2–300 K. It is shown that the transformation from an incoherent to a coherent interface between layers leads to an enhancement of the ferromagnetic coupling, which is accompanied by a modification in the temperature dependence of the resistance and by a grown negative magnetoresistance ratio at room temperature. The influence of grain boundaries on the transport of carriers in the multilayered films is discussed on the basis of modern theoretical approaches

Influence of structural disorder on magnetic and transport properties of (La₀.₇Sr₀.₃)₀.₅(Pr₀.₆₅Ca₀.₃₅)₀.₅MnO₃ films

Magnetic and transport properties of (La₀.₇Sr₀.₃)₀.₅(Pr₀.₆₅Ca₀.₃₅)₀.₅MnO₃ films prepared by a «co-deposition» utilizing the laser-ablation technique are investigated in a wide temperature range. The film deposited at 300 °C has a nano-crystalline disordered structure and exhibits a paramagnetic temperature dependence of the magnetization with a narrow peak (ΔT ≃ 10 K) at TG ≃ 45 K, which can be interpreted as a paramagnetic → superparamagnetic transition. A short-term annealing of the as-deposited film at 750 °C leads to the formation of a high-textured polycrystalline microstructure and to the appearance of ferromagnetic (FM) and metal—insulator (MI) transitions at TC ≃ 240 K and TP ≃ 140 K, respectively. The observed discrepancy between TP and TC values can be ascribed to a percolating nature of the MI transition, with an exponent of 5.3 for the percolating conductivity. The film deposited at Tsub ≃ 740 °C is composed of the lattice strain-free and the lattice-strained crystallites with different lattice parameters and TC‘s, and is consistently described in the framework of the Millis model [A.J. Millis, T. Darling, and A. Migliori, J. Appl. Phys. 83, 1588 (1998)]. For a single-phase crystalline film obtain TC ≃ 270 K and TP ≃ 260 K

Magnetic proximity effect in Pr₀.₅Ca₀.₅MnO₃/La₀.₇Sr₀.₃MnO₃ bilayered films

The magnetotransport properties of Pr₀.₅Ca₀.₅MnO₃/La₀.₇Sr₀.₃MnO₃ bilayer, and Pr₀.₅Ca₀.₅MnO₃ and La₀.₇Sr₀.₃MnO₃ films, deposited on LaAlO₃ (001) substrate by pulse laser deposition have been investigated. The x-ray diffraction and high-resolution electron-microscopy analysis reveals that lattice parameters for the constituent sublayers in the bilayer are very close to that for the individual films. It was found that a ferromagnetic transition in the La₀.₇Sr₀.₃MnO₃ sublayer significantly modifies the magnetotransport properties of the Pr₀.₅Ca₀.₅MnO₃ constituent sublayer, owing to occurrence of a magnetic proximity effect. The main evidences for this effect are an appearance of the exchange bias interaction between the constituent sublayers; a localizedto-itinerant crossover in the system of polarized electrons, which results in formation of the Griffiths-like ferromagnetic state; and an unusual polaron transport of carriers. The experimental results have been analyzed within the framework of modern theoretical approaches

Epitaxial YBa2Cu3O7-8 films : Crucial role of growth-induced linear defects in microwave properties

A significant contribution to high-frequency electromagnetic response of epitaxial YBCO films is supposed to be accounted for growth-induced linear defects. There are two major types of linear defects in the YBCO films : out-of-plane and in-plane edge dislocations. The out-of-plane edge dislocations are shown to play a remarkable role in the surface resistance due to their extended elastic strain fields around a normal core. In-plane edge dislocations do not contribute observably into HF losses, since strain fields around their cores are negligible. The area of suppressed order parameter per one dislocation line was estimated to be 8.10-13) cm2 at 77 K. When out-of- plane edge dislocation density is 1011 lines/cm2, the normal phase fraction in the film volume can reach approximately 10%. The heat instability induced by the linear defects is assumed to enhance the remarkable difference between microwave properties of YBCO single crystals and thin films and results in a nonlinear response

Multi-messenger Observations of a Binary Neutron Star Merger

International audienceOn 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of $\sim 1.7\,{\rm{s}}$ with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg(2) at a luminosity distance of ${40}_{-8}^{+8}$ Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 $\,{M}_{\odot }$. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at $\sim 40\,{\rm{Mpc}}$) less than 11 hours after the merger by the One-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ∼10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position $\sim 9$ and $\sim 16$ days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC 4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta