Magnetic Tunneling Junctions for biosensors: From the growth to the detection

In the last ten years, magnetoelectronics has emerged as a promising new platform technology for biosensor and biochip development. In particular, magnetoresistive-based sensors, conventionally used as read heads in hard disk drives, have been used in combination with biologically functionalized magnetic labels to demonstrate the detection of molecular recognition. In this paper, the growth and fabrication of spintronic transducers based on the magnetoresistance of tunneling magnetic junctions are described. Moreover the detection of 250 nm streptavidin magnetic beads is presented

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

Bandstructure line-up of epitaxial Fe/MgO/Ge heterostructures: A combined x-ray photoemission spectroscopy and transport study

The bandstructure line-up of Fe/MgO/Ge heterostructures with various Ge doping has been determined by x-ray photoemission spectroscopy. The MgO layer causes a sizable depinning of the Fermi level in Ge for light n-1015 cm−3 and moderate p-doping 1018 cm−3, but not for heavy n-doping 1020 cm−3. The Fermi level instead stays essentially in the middle of the MgO gap for all the investigated doping. This picture agrees with transport measurements only for moderate n- or p-doping, while we demonstrate that for heavy n-doping the analysis of the conductance versus temperature fails in predicting the Schottky barrier height

Epitaxial growth of Fe/MgO/Ge(001) heterostructures

We report on the growth of epitaxial Fe/MgO heterostructures on Ge(0 0 1) by Molecular Beam Epitaxy. The better crystal quality and interfacial chemical sharpness at the oxide–semiconductor interface have been obtained by growing MgO at room temperature, followed by a post-annealing at 773 K, on top of a p(2 1)-Ge(0 0 1) clean surface. The growth of Fe at room temperature followed by annealing at 473 K gives the best epitaxial structure with optimized crystallinity of each layer compatible with limited chemical interdiffusion. Tunneling devices based on the epitaxial Fe/MgO/Ge heterostructure have been micro-fabricated and tested in order to probe the electrical properties of the MgO barrier. The current–voltage characteristics clearly show that tunneling is the dominant phenomenon, thus indicating that this system is very promising for practical applications in electronics and spintronics

Epitaxial growth of Fe/BaTiO3 heterostructures

Epitaxial growth of Fe/BaTiO3 heterostructure

Overview of International Waste Management Activities in Fusion

The minimization of active waste from the operation and decommissioning of a fusion power plant is a common goal of fusion development programs in Europe and in the US. Approaches differ, according to national regulations, and include reuse and recycling, clearance for non-active disposal or free-release recycling, and shallow land burial. Adopting the minimization of active waste volume as a design requirement leads to a Low Activation Design if properly optimized for materials choices. Power plant studies, both ARIES in the US and the PPCS in Europe, are adopting strategies to meet such requirements. International collaboration, particularly in the frame of an IEA co-operative program, provides benefits in the development of waste management strategie

Dispositivo rilevatore ottico spintronico

Dispositivo rilevatore ottico spintronic

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