127 research outputs found

    Magnetic properties of GdT2T_2Zn20_{20} (T = Fe, Co) investigated by X-ray diffraction and spectroscopy

    Get PDF
    We investigate the magnetic and electronic properties of the GdT2T_2Zn20_{20} (TT = Fe and Co) compounds using X-ray resonant magnetic scattering (XRMS), X-ray absorption near-edge structure (XANES) and X-ray magnetic circular dichroism (XMCD) techniques. The XRMS measurements reveal that the GdCo2_2Zn20_{20} compound has a commensurate antiferromagnetic spin structure with a magnetic propagation vector τ\vec{\tau} = (12,12,12)(\frac{1}{2},\frac{1}{2},\frac{1}{2}) below the N\'eel temperature (TNT_N \sim 5.7 K). Only the Gd ions carry a magnetic moment forming an antiferromagnetic structure with magnetic representation Γ6\Gamma_6. For the ferromagnetic GdFe2_2Zn20_{20} compound, an extensive investigation was performed at low temperature and under magnetic field using XANES and XMCD techniques. A strong XMCD signal of about 12.5 %\% and 9.7 %\% is observed below the Curie temperature (TCT_C \sim 85 K) at the Gd-L2L_2 and L3L_3 edges, respectively. In addition, a small magnetic signal of about 0.06 %\% of the jump is recorded at the Zn KK-edge suggesting that the Zn 4pp states are spin polarized by the Gd 5dd extended orbitals

    A novel plasma jet with RF and HF coupled electrodes

    Get PDF
    In order to achieve low processing temperature and efficient coatings deposition for manufacturing applications, a novel torch has been developed that couples in a double DBD design high frequency (HF ~17 kHz) and radio frequency (RF ~27 MHz) excitations. The design allows to obtain a stable RF plasma also in reactive processes and with the possibility to control on the treated substrates ions flux and surface charging, avoiding the micro-discharges. The plasma has been electrically and optically characterized by emission spectroscopy

    Action of Coriandrum sativum L. Essential Oil upon Oral Candida albicans Biofilm Formation

    Get PDF
    The efficacy of extracts and essential oils from Allium tuberosum, Coriandrum sativum, Cymbopogon martini, Cymbopogon winterianus, and Santolina chamaecyparissus was evaluated against Candida spp. isolates from the oral cavity of patients with periodontal disease. The most active oil was fractionated and tested against C. albicans biofilm formation. The oils were obtained by water-distillation and the extracts were prepared with macerated dried plant material. The Minimal Inhibitory Concentration—MIC was determined by the microdilution method. Chemical characterization of oil constituents was performed using Gas Chromatography and Mass Spectrometry (GC-MS). C. sativum activity oil upon cell and biofilm morphology was evaluated by Scanning Electron Microscopy (SEM). The best activities against planktonic Candida spp. were observed for the essential oil and the grouped F8–10 fractions from C. sativum. The crude oil also affected the biofilm formation in C. albicans causing a decrease in the biofilm growth. Chemical analysis of the F8–10 fractions detected as major active compounds, 2-hexen-1-ol, 3-hexen-1-ol and cyclodecane. Standards of these compounds tested grouped provided a stronger activity than the oil suggesting a synergistic action from the major oil constituents. The activity of C. sativum oil demonstrates its potential for a new natural antifungal formulation

    Coupling of magnetic order and charge transport in the candidate Dirac semimetal EuCd2_2As2_2

    Get PDF
    We use resonant elastic x-ray scattering to determine the evolution of magnetic order in EuCd2_2As2_2 below TN=9.5T_\textrm{N}=9.5\,K, as a function of temperature and applied magnetic field. We find an A-type antiferromagneticstructure with in-plane magnetic moments, and observe dramatic magnetoresistive effects associated with field-induced changes in the magnetic structure and domain populations. Our \textit{ab initio} electronic structure calculations indicate that the Dirac dispersion found in the nonmagnetic Dirac semimetal Cd3_3As2_2 is also present in EuCd2_2As2_2, but is gapped for T<TNT < T_\textrm{N} due to the breaking of C3C_3 symmetry by the magnetic structure.Comment: Supplemental information attached to preprin
    corecore