Influence of the interface morphology on the magnetization of Magnetic/Non-Magnetic (Fe/Cu) multilayers: a Monte Carlo investigation

A Monte Carlo investigation was used to study the magnetization of a Heisenberg multilayers system. Our model consists of an alternate staking of Magnetic and Non-Magnetic layers (M/NM) with disordered interfaces. The results indicate that the magnetization of multilayers M/NM depends on the atomic composition, the interface morphology and the exchange interactions at the interface.A Monte Carlo investigation was used to study the magnetization of a Heisenberg multilayers system. Our model consists of an alternate staking of Magnetic and Non-Magnetic layers (M/NM) with disordered interfaces. The results indicate that the magnetization of multilayers M/NM depends on the atomic composition, the interface morphology and the exchange interactions at the interface

Mössbauer study and Monte Carlo simulations of the hyperfine field distribution in Magnetic/Non-Magnetic (M/NM) multilayers

Using a Monte Carlo numerical method, we perform a complementary analysis of the hyperfine field distribution in Magnetic/Non-Magnetic (M=Fe/NM=Cu) multilayers and a comparison with Mössbauer experiment results of [Fe(40)=Cu(20)]20 multilayers. From differing relaxation rates for spins with few near neighbor spins and particularly those located at the interface, the Mössbauer result can be simulated. Our model consists of an alternate stacking of magnetic and non-magnetic layers (MnM/NMnNM) with disordered interface. The simulation results confirm that the concentration of interface alloys (M1-xNMx) and magnetic layer thickness modify systemically the magnetization distribution in the M/NM multilayers. The result is in agreement with Mössbauer experimental analysis

Atomic scale simulation of epitaxial growth: Cases of GaAs/GaAs and CdTe/GaAs

We present a kinetic Monte Carlo model describing the growth by molecular beam epitaxy (MBE) of semiconductor compounds and including a local photoemission model with reflection high-energy electron diffraction (RHEED) intensity for comparison. We investigate the cases of both homoepitaxial and heteroepitaxial growth. The valence force field approximation is used for the strain energy calculations in mismatched thin films In homoepitaxial growth of GaAs, we have study the variations of photoemission current and RHEED intensity and examined the GaAs morphology. In high lattice mismatch heteroepitaxial growth (CdTe/GaAs), we have shown the formation of grooves corresponding to (111) facets, precursor to the formation of misfit defects.We present a kinetic Monte Carlo model describing the growth by molecular beam epitaxy (MBE) of semiconductor compounds and including a local photoemission model with reflection high-energy electron diffraction (RHEED) intensity for comparison. We investigate the cases of both homoepitaxial and heteroepitaxial growth. The valence force field approximation is used for the strain energy calculations in mismatched thin films In homoepitaxial growth of GaAs, we have study the variations of photoemission current and RHEED intensity and examined the GaAs morphology. In high lattice mismatch heteroepitaxial growth (CdTe/GaAs), we have shown the formation of grooves corresponding to (111) facets, precursor to the formation of misfit defects

THE IRON SPIN TEXTURE IN ANNEALED AMORPHOUS Fe/Tb MULTI-LAYERS

Fe/Tb multilayers have been obtained by vacuum evaporation with Tb-layer thickness fixed to 40Å and amorphous Fe-layer thickness fixed to 19Å. 57Fe-Mössbauer spectrometry was used to obtain information on the structure and the spin texture of the multilayers before and after annealing at 530K for different durations of the annealing. The Mössbauer results indicate that the Perpendicular Magnetic Anisotropy (PMA) was stabilised and reinforced after annealing.Fe/Tb multilayers have been obtained by vacuum evaporation with Tb-layer thickness fixed to 40Å and amorphous Fe-layer thickness fixed to 19Å. 57Fe-Mössbauer spectrometry was used to obtain information on the structure and the spin texture of the multilayers before and after annealing at 530K for different durations of the annealing. The Mössbauer results indicate that the Perpendicular Magnetic Anisotropy (PMA) was stabilised and reinforced after annealing

Electronic structure of the Magnesium hydride molecular ion

In this paper, using a standard quantum chemistry approach based on pseudopotentials for atomic core representation, Gaussian basis sets, and effective core polarization potentials, we investigate the electronic properties of the MgH$^+$ ion. We first determine potential energy curves for several states using different basis sets and discuss their predicted accuracy by comparing our values of the well depths and position with other available results. We then calculate permanent and transition dipole moments for several transitions. Finally for the first time, we calculate the static dipole polarizability of MgH$^+$ as function of the interatomic distance. This study represents the first step towards the modeling of collisions between trapped cold Mg$^+$ ions and H$_2$ molecules.Comment: submitted to J. Phys. B, special issue on Cold trapped ion

Aging characterization of metals for exhaust systems

The mechanical characteristics of four materials used in automotive exhaust systems have been compared after an aging treatment to evaluate the combined effects of thermo-mechanical fatigue and corrosion. For this purpose, an experimental aging procedure has been developed. This procedure is composed of chemical, thermal and mechanical cycles, which are combined and repeated to simulate the actual operating conditions of automotive exhaust systems. Three austenitic steels (AISI 309, AISI 316Ti, and AISI 321) and a nickel-based alloy (Inconel 625) are tested. The results show that Inconel 625 and AISI 309 are less affected by the aging process than the other material

Theoretical study of atomic excitation by impact of protons in the variational formalism

Schwinger's variational principle is used to evaluate excitation cross-sections of hydrogen atom by proton impact in a range of energies excluding a pertubative treatment. To describe the strong coupling between the excitation and the capture channels that exists at low energies, the continuum states have been introduced in the total wave function. Our results show that these states can describe properly the projectile capture states