J. Milano

Magnetization reversal and anomalous dependence of the coercive field with temperature in MnAs epilayers grown on GaAs

The magnetic properties of MnAs epilayers have been investigated for two different substrate orientations: GaAs(100) and GaAs(111). We have analyzed the magnetization reversal under magnetic field at low temperatures, determining the anisotropy of the films. The results, based on the shape of the magnetization loops, suggest a domain movement mechanism for both types of samples. The temperature dependence of the coercivity of the films has been also examined, displaying a generic anomalous reentrant behavior at T

Combined impurity and band effects on the appearance of inverse giant magnetoresistance in Cu/Fe multilayers with Cr

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Large perpendicular magnetic anisotropy in magnetostrictive Fe1 xGax thin films

200 K. This feature is independent of the substrate orientation and films thickness and may be associated to the appearance of new pinning centers due to the nucleation of the

Magnetic properties of Fe/ZnSe/Fe trilayers

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Tunneling through a semiconducting spacer: complex band predictions vs. thin film calculations

-phase at high temperatures.

Electronic and magnetic properties of the inverse magnetoresistant Fe1−xCoxSi alloys

We have studied the dependence of impurity vs band effects in the appearance of inverse giant magnetoresistance (IGMR) in Cu/Fe superlattices with Cr. Current in plane (CIP) and current perpendicular to the plane geometries are considered. For the calculation of the conductivities, we have used the linearized Boltzmann equation in the relaxation time approximation. Cr impurity effects are taken into account through the spin-dependent relaxation times and the band effects through the semiclassical velocities obtained from the local-density approximation calculated electronic structure. The larger the Cr/Fe hybridization strength, the bigger is the tendency towards IGMR. In particular, in CIP geometry roughness at these interfaces increases the IGMR range. The calculated giant magnetoresistance ratios have been compared with the experimental results. From this comparison we conclude that the experimental data can only be explained by taking into account Cr bands.

Large perpendicular magnetic anisotropy in magnetostrictiveFe1−xGaxthin films

In this work we report the appearence of a large perpendicular magnetic anisotropy (PMA) in Fe1−xGax thin films grown onto ZnSe/GaAs(100). This arising anisotropy is related to the tetragonal metastable phase in as-grown samples recently reported [M. Eddrief {\it et al.}, Phys. Rev. B {\bf 84}, 161410 (2011)]. By means of ferromagnetic resonance studies we measured PMA values up to ∼ 5×105 J/m3. PMA vanishes when the cubic structure is recovered upon annealing at 300∘C. Despite the important values of the magnetoelastic constants measured via the cantilever method, the consequent magnetoelastic contribution to PMA is not enough to explain the observed anisotropy values in the distorted state. {\it Ab initio} calculations show that the chemical ordering plays a crucial role in the appearance of PMA. Through a phenomenological model we are able to explain that an excess of next nearest neighbour Ga pairs (B2-like ordering) along the perpendicular direction arises as the source of PMA in Fe1−xGax thin films.

Large perpendicular magnetic anisotropy in magnetostrictive Fe

Abstract The magnetic properties of Fe/Zn/Fe trilayers have been studied by ferromagnetic resonance and magnetization measurements. These measurements have been used to investigate the magnetic anisotropy of the iron layers and the magnetic coupling across the semiconductor spacer. The angular dependence of the resonance spectra has been measured in-plane and out-of-plane in order to deduce magnetic anisotropy constants of the samples. Experimental data were fitted by using an energy-density expression that includes bulk cubic anisotropy, growth-induced uniaxial in-plane anisotropy and perpendicular-surface anisotropy terms. A small ferromagnetic coupling is observed in the trilayers with spacer thickness up to 50 A .

_{1-x}

Using a simple tight-binding model, we compare the limitations of the tunnelling predictions coming out of the complex band structure of a semiconductor with the output of thin film calculations done for the same semiconducting spacer but considering it to be of finite width, and sandwiched by metallic electrodes. The comparison is made as a function of spacer width and interfacial roughness.

Ga

Abstract The alloy Fe 1− x Co x Si shows a remarkable behaviour, while the two extremes are both nonmagnetic almost all the intermediates show magnetic order, specially in the Fe-rich region. We present here ab initio calculations within the LSDA approximation for these compounds and show that they behave as half metals for x ⩽0.25. This explains the linear dependence on x of the magnetic moment in this region. We also explain the magnetic behaviour for larger concentrations.