ABSTRACT
Orbital hybridization at the Co/C60 interface been has proved to strongly enhance the magnetic anisotropy of the cobalt layer, promoting such hybrid systems as appealing components for sensing and memory devices. Correspondingly, the same hybridization induces substantial variations in the ability of the Co/C60 interface to support spin-polarized currents and can bring out a spin-filtering effect. The knowledge of the effects at both sides allows for a better and more complete understanding of interfacial physics. In this paper we investigate the Co/C60 bilayer in the role of a spin-polarized electrode in the La0.7Sr0.3MnO3/SrTiO3/C60/Co configuration, thus substituting the bare Co electrode in the well-known La0.7Sr0.3MnO3/SrTiO3/Co magnetic tunnel junction. The study revealed that the spin polarization (SP) of the tunneling currents escaping from the Co/C60 electrode is generally negative: i.e., inverted with respect to the expected SP of the Co electrode. The observed sign of the spin polarization was confirmed via DFT calculations by considering the hybridization between cobalt and molecular orbitals.
ABSTRACT
In the past few years, researchers have focused on the design and development of three-dimensional (3D) advanced scaffolds, which offer significant advantages in terms of cell performance. The introduction of magnetic features into scaffold technology could offer innovative opportunities to control cell populations within 3D microenvironments, with the potential to enhance their use in tissue regeneration or in cell-based analysis. In the present study, 3D fully biodegradable and magnetic nanocomposite scaffolds for bone tissue engineering, consisting of a poly(ε-caprolactone) (PCL) matrix reinforced with iron-doped hydroxyapatite (FeHA) nanoparticles, were designed and manufactured using a rapid prototyping technique. The performances of these novel 3D PCL/FeHA scaffolds were assessed through a combination of theoretical evaluation, experimental in vitro analyses and in vivo testing in a rabbit animal model. The results from mechanical com- pression tests were consistent with FEM simulations. The in vitro results showed that the cell growth in the magnetized scaffolds was 2.2-fold greater than that in non-magnetized ones. In vivo experiments further suggested that, after only 4 weeks, the PCL/FeHA scaffolds were completely filled with newly formed bone, proving a good level of histocompatibility. All of the results suggest that the introduction of magnetic features into biocompatible materials may confer significant advantages in terms of 3D cell assembly.
Subject(s)
Bone Regeneration/physiology , Femoral Fractures/therapy , Magnetite Nanoparticles/chemistry , Nanofibers/chemistry , Polyesters/chemistry , Tissue Scaffolds , Animals , Bone Substitutes/chemical synthesis , Equipment Failure Analysis , Femoral Fractures/pathology , Femoral Fractures/physiopathology , Iron/chemistry , Magnetite Nanoparticles/ultrastructure , Male , Nanocomposites/chemistry , Nanocomposites/ultrastructure , Nanofibers/ultrastructure , Particle Accelerators , Prosthesis Design , Rabbits , Surface Properties , Tissue Engineering/instrumentation , Treatment OutcomeABSTRACT
Memristors are one of the most promising candidates for future information and communications technology (ICT) architectures. Two experimental proofs of concept are presented based on the intermixing of spintronic and memristive effects into a single device, a magnetically enhanced memristor (MEM). By exploiting the interaction between the memristance and the giant magnetoresistance (GMR), a universal implication (IMP) logic gate based on a single MEM device is realized.
ABSTRACT
In hopping magnetoresistance of doped insulators, an applied magnetic field shrinks the electron (hole) s-wave function of a donor or an acceptor and this reduces the overlap between hopping sites resulting in the positive magnetoresistance quadratic in a weak magnetic field, B. We extend the theory of hopping magnetoresistance to states with nonzero orbital momenta. Different from s states, a weak magnetic field expands the electron (hole) wave functions with positive magnetic quantum numbers, m>0, and shrinks the states with negative m in a wide region outside the point defect. This together with a magnetic-field dependence of injection/ionization rates results in a negative weak-field magnetoresistance, which is linear in B when the orbital degeneracy is lifted. The theory provides a possible explanation of a large low-field magnetoresistance in disordered π-conjugated organic materials.