Electric field control of magnetic anisotropies and magnetic coercivity in Fe/BaTiO3 (001) heterostructures

Electric field control of magnetic anisotropies and magnetic coercivity in Fe/BaTiO3 (001) heterostructure

Epitaxial growth of Fe/BaTiO3 heterostructures

Epitaxial growth of Fe/BaTiO3 heterostructure

Observation of anomalous acoustic phonon dispersion in SrTiO3 by broadband stimulated Brillouin scattering

Observation of anomalous acoustic phonon dispersion in SrTiO3 by broadband stimulated Brillouin scatterin

Sharp Fe/MgO/Ge(001) epitaxial heterostructures for tunneling junctions

We report on the growth of epitaxial Fe/MgO/Ge(001) heterostructures by molecular beam epitaxy. The lowest oxidation and highest sharpness of the MgO/Ge interface, corresponding to a transition layer on the order of one Ge unit cell, is obtained for room temperature growth of the MgO layer followed by annealing in a vacuum at 500 C. In these conditions, the MgO layer grows epitaxially on Ge(001) with the [110] direction parallel to the [100] direction of Ge, at variance with the cube-on-cube growth on Si(001) and GaAs(001). However, in some cases, the cube-on-cube growth mode of MgO on Ge competes with the mode involving a 45 rotation, as revealed by transmission electron microscopy and photoelectron diffraction data on MgO films grown at 300 C without postannealing, and on p-doped Ge substrates. For the Fe overlayer, in all the cases reported, room temperature growth followed by annealing up to 200 C gives rise to a sharp interface and the well-known 45 rotation of the Fe lattice with respect to the MgO lattice

Aberration corrected scanning transmission electron microscopy and electro energy loss spectroscopy studies of epitaxial Fe/MgO/(001)Ge heterostructures

Aberration correction in the scanning transmission electron microscope combined with electron energy loss spectroscopy allows simultaneous mapping of the structure, the chemistry and even the electronic properties of materials in one single experiment with spatial resolutions of the order of one A ° ngstro¨m. Here the authors will apply these techniques to the characterization of epitaxial Fe/MgO/(001)Ge and interfaces with possible applications for tunneling junctions, and the authors will show that epitaxial MgO films can be grown on a (001)Ge substrates by molecular beam epitaxy and how it is possible to map the chemistry of interfaces with atomic resolution

Oxygen vacancies and induced changes in the electronic and magnetic structures of La0.66Sr0.33MnO3: A combined ab initio and photoemission study

The effect of oxygen vacancies on the electronic and magnetic properties of La0.66Sr0.33MnO3 LSMO has been investigated by means of ab initio calculations within the density-functional formalism combined with photoemission. The simulations show that the introduction of oxygen vacancies causes a shift of the valenceband features toward higher binding energies and an increase of the degree of covalency of Mn bondings. The Mn magnetic moments undergo some changes, keeping, however, the situation relatively close to the ideal nondefective system: in none of the different vacancy configurations, a drastic charge or spin rearrangement occurs. There is, though, an important vacancy-induced drawback: half-metallicity, typical of the perfectly stoichiometric system, is generally lost due to defective bands that cross the Fermi level. Photoemission experiments performed on epitaxial thin films of LSMO with different contents of oxygen vacancies grown by pulsed laser deposition essentially confirm theoretical predictions. Our findings clearly indicate that the control over oxygen deficiency should therefore be experimentally achieved to avoid unwanted consequences in terms of spin-injection efficiency

Proximity effects induced by a gold layer on La0.67Sr0.33MnO3 thin films

We report about La0.67Sr0.33MnO3 single crystal manganite thin films in interaction with a gold capping layer. With respect to uncoated manganite layers of the same thickness, Au-capped 4 nm-thick manganite films reveal a dramatic reduction (about 185 K) of the Curie temperature TC and a lower saturation low-temperature magnetization M0. A sizeable TC reduction (about 60 K) is observed even when an inert SrTiO3 layer is inserted between the gold film and the 4 nm-thick manganite layer, suggesting that this effect might have an electrostatic origin