Search results for "electrons"
showing 10 items of 1325 documents
Enhancing Light Emission in Interface Engineered Spin-OLEDs Through Spin-Polarized Injection at High Voltages
2016
The quest for a spin-polarized organic light emitting diode (spin-OLED) is a common goal in the emerging fields of molecular electronics and spintronics. In this device two ferromagnetic electrodes are used to enhance the electroluminescence intensity of the OLED through a magnetic control of the spin polarization of the injected carriers. The major difficulty is that the driving voltage of an OLED device exceeds of a few volts, while spin injection in organic materials is only efficient at low voltages. We report here the fabrication of a spin-OLED that uses a conjugated polymer as bipolar spin collector layer and ferromagnetic electrodes. Through a careful engineering of the organic/inorg…
Doping effects on the magnetic frustration in the honeycomb iridates
2015
We investigate the doping effects of magnetic and nonmagnetic impurities injected to the honeycomb iridate sample of Na2IrO3 . Both the doping result in changing the ordering temperature as well as the Curie-Weiss temperature of the parent sample as a consequence of enhancement of the lattice frustration, screening of the Ir atoms and spin-orbit effects that reflects in the susceptibility and specific heat measurements. Our findings are corroborated by a detailed comparative study of various magnetic and nonmagnetic impurity atoms that have notable effects on different electronic properties of the doped compounds.
Completely compensated ferrimagnetism and sublattice spin crossing in the half-metallic Heusler compound Mn1.5FeV0.5Al
2016
The Slater-Pauling rule states that L21 Heusler compounds with 24 valence electrons do never exhibit a total spin magnetic moment. In case of strongly localized magnetic moments at one of the atoms (here Mn) they will exhibit a fully compensated half-metallic ferrimagnetic state instead, in particular, when symmetry does not allow for antiferromagnetic order. With aid of magnetic and anomalous Hall effect measurements it is experimentally demonstrated that Mn1.5V0.5FeAl follows such a scenario. The ferrimagnetic state is tuned by the composition. A small residual magnetization, that arises due to a slight mismatch of the magnetic moments in the different sublattices results in a pronounced …
Probing the spin dimensionality in single-layer CrSBr van der Waals heterostructures by magneto-transport measurements
2022
Two-dimensional (2D) magnetic materials offer unprecedented opportunities for fundamental physics and applied research in spintronics and magnonics. Beyond the pioneering studies on 2D CrI3 and Cr2Ge2Te6, this emerging field has expanded to 2D antiferromagnets exhibiting different spin anisotropies and textures. Of particular interest is the layered metamagnet CrSBr, a relatively air-stable semiconductor formed by antiferromagnetically-coupled ferromagnetic layers (Tc~150 K) that can be exfoliated down to the single-layer. It presents a complex magnetic behavior with a dynamic magnetic crossover leading to a low-temperature hidden order below T*~40 K. Here, we inspect the magneto-transport …
Giant Negative Magnetoresistance Driven by Spin-Orbit Coupling at the LaAlO3/SrTiO3 Interface
2015
The LaAlO3/SrTiO3 interface hosts a two-dimensional electron system that is unusually sensitive to the application of an in-plane magnetic field. Low-temperature experiments have revealed a giant negative magnetoresistance (dropping by 70%), attributed to a magnetic-field induced transition between interacting phases of conduction electrons with Kondo-screened magnetic impurities. Here we report on experiments over a broad temperature range, showing the persistence of the magnetoresistance up to the 20 K range--indicative of a single-particle mechanism. Motivated by a striking correspondence between the temperature and carrier density dependence of our magnetoresistance measurements we prop…
Different Look at the Spin State ofCo3+Ions in aCoO5Pyramidal Coordination
2004
Using soft-x-ray absorption spectroscopy at the Co ${L}_{2,3}$ and O $K$ edges, we demonstrate that the ${\mathrm{Co}}^{3+}$ ions with the ${\mathrm{CoO}}_{5}$ pyramidal coordination in the layered ${\mathrm{Sr}}_{2}{\mathrm{CoO}}_{3}\mathrm{Cl}$ compound are unambiguously in the high spin state. Our result questions the reliability of the spin state assignments made so far for the recently synthesized layered cobalt perovskites and calls for a reexamination of the modeling for the complex and fascinating properties of these new materials.
Electronic structure of two crystallographic forms ofBaRuO3
2000
Electronic structure calculations have been performed to explain the difference in the electronic properties of two crystallographic forms of ${\mathrm{BaRuO}}_{3}.$ The calculations can explain the qualitatively different resistivities of isoelectronic $4H$- and $9R$-${\mathrm{BaRuO}}_{3}$ below 100 K. The difference in symmetry between the hexagonal four-layer ${\mathrm{BaRuO}}_{3}$ and the rhombohedral nine-layer compound allows the formation of a gap for the later. The electronic structure of these hexagonal perovskites is compared with the more familiar cubic perovskite ${\mathrm{CaRuO}}_{3}.$
Efficient Spin Torques in Antiferromagnetic CoO/Pt Quantified by Comparing Field- and Current-Induced Switching
2020
We achieve current-induced switching in collinear insulating antiferromagnetic CoO/Pt, with fourfold in-plane magnetic anisotropy. This is measured electrically by spin Hall magnetoresistance and confirmed by the magnetic field-induced spin-flop transition of the CoO layer. By applying current pulses and magnetic fields, we quantify the efficiency of the acting current-induced torques and estimate a current-field equivalence ratio of 4×10^{-11} T A^{-1} m^{2}. The Neel vector final state (n⊥j) is in line with a thermomagnetoelastic switching mechanism for a negative magnetoelastic constant of the CoO.
Magnetic Coupling in Y3Fe5O12/Gd3Fe5O12 Heterostructures
2021
Ferrimagnetic ${\mathrm{Y}}_{3}{\mathrm{Fe}}_{5}{\mathrm{O}}_{12}$ (YIG) is the prototypical material for studying magnonic properties due to its exceptionally low damping. By substituting the yttrium with rare earth elements that have a net magnetic moment, we can introduce an additional spin degree of freedom. Here, we study the magnetic coupling in epitaxial ${\mathrm{Y}}_{3}{\mathrm{Fe}}_{5}{\mathrm{O}}_{12}$/${\mathrm{Gd}}_{3}{\mathrm{Fe}}_{5}{\mathrm{O}}_{12}$ (YIG/GIG) heterostructures grown by pulsed laser deposition. From bulk sensitive magnetometry and surface sensitive spin Seebeck effect and spin Hall magnetoresistance measurements, we determine the alignment of the heterostruct…
Multiferroic BiFeO<inf>3</inf> for conductance control at the LaAlO<inf>3</inf>/SrTiO<inf>3</inf>-interface
2015
Multiferroic materials possessing both magnetic and ferroelectric order enable in principle to switch order parameters using not the direct reciprocal field, e.g. to switch the magnetization by an electric field or the electric polarization by a magnetic field. A recent breakthrough was achieved by the demonstration of the ferromagnetic switching of a Co layer with an electric field employing the multiferroic BiFeO 3 [1]. The latter material is a perovskite based oxide that shows stable ferro-electricity as well as an antiferromagnetic order at room temperature [2,3]. Due to a Dzyaloshinskii-Moriya interaction induced by rotation of oxygen octahedra leading to noncollinear Fe-O-Fe bonds a s…