Pseudospin Dynamics of the One-Dimensional S = ½ XY System PrCl3 Studied by Electronic Raman Scattering

Direct confirmation of the one-dimensional S = ½ XY character of the interactions between the pseudospins of the Pr3+ ions in PrCl3 is obtained through a study of the pseudospin dynamics by means of electronic Raman scattering, with and without a magnetic field. This is concluded from an analytic calculation of the spectral moments and from a numerical finite-chain calculation of the line shapes, both of which are in excellent agreement with the experimental data

Temperature dependence of Eu-related EPR spectra in CsBr:Eu needle image plates

Vacuum deposited CsBr needle plates, doped with Eu2+, have been investigated with Q (~34 GHz) and W (~95 GHz) band electron paramagnetic resonance in a large temperature interval (4K – room temperature). At low temperatures (<35K) two Eu-related centers were found with different symmetry (tetragonal and orthorhombic), while in earlier studies at room temperature only one center was found with tetragonal symmetry. Possible models for the three defects are investigated, taking into account their temperature behavior, their symmetry and the atypical values of their zero-field splitting parameters

Relaxation mechanisms in ultra-low damping Fe80Co20 thin films

Ferromagnetic thin films with ultra-low damping constants (α) are intensively studied for applications in spintronic devices. We report here the influence of the sputtering conditions (deposition power and temperature) on the magnetic properties of Fe80Co20/Ta bilayers deposited on MgO (0 0 1) and Si (0 0 1) which have been studied using ferromagnetic resonance (FMR) and magneto-optic Kerr-effect (MOKE) techniques. We have found that for the studied fabrication conditions the samples deposited on MgO (0 0 1) have [1 0 0] epitaxial growth with a cubic anisotropy field Hc ~ 300 Oe, while those sputtered on Si (0 0 1) grow polycrystalline with a small uniaxial anisotropy due to the deposition conditions. With measurements at different excitation frequencies we have determined exceptionally low damping values for ferromagnetic conductors (α ~ 3 × 10−3), which makes the Fe80Co20/Ta system an excellent candidate for future applications in spintronic devices. From the analysis of the dependence of the FMR linewidth on the orientation of the applied magnetic field and the excitation frequency in FMR experiments, we were able to separate the contribution of the different relaxation mechanisms (Gilbert damping, two magnon scattering and mosaicity) to the linewidth and to explain quantitatively the observed behavior.Fil: Velázquez Rodriguez, Daniel. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Gomez, Javier Enrique. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Alejandro, Gabriela. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Avilés Félix, Luis. Universite Grenoble Alpes; FranciaFil: Van Landeghem, Melissa. Universite Libre de Bruxelles. Universiteit Antwerpen; BélgicaFil: Goovaerts, Etienne. Universite Libre de Bruxelles. Universiteit Antwerpen; BélgicaFil: Butera, Alejandro Ricardo. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Universidad Nacional de Cuyo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentin

Identification of vanadium dopant sites in the metal-organic framework DUT-5(Al)

Studying the structural environment of the V-IV ions doped in the metal-organic framework (MOF) DUT-5(Al) (((AlOH)-O-III)BPDC) with electron paramagnetic resonance (EPR) reveals four different vanadium-related spectral components. The spin-Hamiltonian parameters are derived by analysis of X-, Q- and W-band powder EPR spectra. Complementary Q-band Electron Nuclear DOuble Resonance (ENDOR) experiments, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDX), X-Ray Diffraction (XRD) and Fourier Transform InfraRed (FTIR) measurements are performed to investigate the origin of these spectral components. Two spectral components with well resolved V-51 hyperfine structure are visible, one corresponding to V-IV-O substitution in a large (or open) pore and one to a narrow (or closed) pore variant of this MOF. Furthermore, a broad structureless Lorentzian line assigned to interacting vanadyl centers in each other's close neighborhood grows with increasing V-concentration. The last spectral component is best visible at low V-concentrations. We tentatively attribute it to (V-IV=O)(2+) linked with DMF or dimethylamine in the pores of the MOF. Simulations using these four spectral components convincingly reproduce the experimental spectra and allow to estimate the contribution of each vanadyl species as a function of V-concentration