Search results for "Spintronics"
showing 10 items of 231 documents
Dicopper(II) Anthraquinophanes as Multielectron Reservoirs for Oxidation and Reduction: A Joint Experimental and Theoretical Study
2014
Two new dinuclear copper(II) metallacyclophanes with 1,4-disubstituted 9,10-anthraquinonebis(oxamate) bridging ligands are reported that can reversibly take and release electrons at the redox-active ligand and metal sites, respectively, to give the corresponding mono- and bis(semiquinonate and/or catecholate) Cu(II)2 species and mixed-valent Cu(II)/Cu(III) and high-valent Cu(III)2 ones. Density functional calculations allow us to give further insights on the dual ligand- and metal-based character of the redox processes in this novel family of antiferromagnetically coupled di- copper(II) anthraquinophanes. This unique ability for charge storage could be the basis for the development of new k…
Dilution-Triggered SMM Behavior under Zero Field in a Luminescent Zn2Dy2 Tetranuclear Complex Incorporating Carbonato-Bridging Ligands Derived from A…
2013
The synthesis, structure, magnetic, and luminescence properties of the Zn2Dy2 tetranuclear complex of formula {(mu(3)-CO3)2[Zn(mu-L)Dy(NO3)}(2)}center dot 4CH(3)OH (1), where H2L is the compartmental ligand N,N',N"-trimethyl-N,N"-bis(2-hydroxy-3-methoxy-5-methylbenzyl)diethylenetriamine, are reported. The carbonate anions that bridge two Zn(mu-L)Dy units come from the atmospheric CO2 fixation in a basic medium. Fast quantum tunneling relaxation of the magnetization (QTM) is very effective in this compound, so that single-molecule magnet (SMM) behavior is only observed in the presence of an applied dc field of 1000 Oe, which is able to partly suppress the QTM relaxation process. At variance,…
Electroburning of few-layer graphene flakes, epitaxial graphene, and turbostratic graphene discs in air and under vacuum
2015
Graphene-based electrodes are very promising for molecular electronics and spintronics. Here we report a systematic characterization of the electroburning (EB) process, leading to the formation of nanometer-spaced gaps, on different types of few-layer graphene (namely mechanically exfoliated graphene on SiO2, graphene epitaxially grown on the C-face of SiC and turbostratic graphene discs deposited on SiO2) under air and vacuum conditions. The EB process is found to depend on both the graphene type and on the ambient conditions. For the mechanically exfoliated graphene, performing EB under vacuum leads to a higher yield of nanometer-gap formation than working in air. Conversely, for graphene…
Field-driven domain wall motion under a bias current in the creep andflow regimes in Pt/[CoSiB/Pt](N) nanowires
2016
AbstractThe dynamics of magnetic domain wall (DW) in perpendicular magnetic anisotropy Pt/[CoSiB/Pt]N nanowires was studied by measuring the DW velocity under a magnetic field (H) and an electric current (J) in two extreme regimes of DW creep and flow. Two important findings are addressed. One is that the field-driven DW velocity increases with increasing N in the flow regime, whereas the trend is inverted in the creep regime. The other is that the sign of spin current-induced effective field is gradually reversed with increasing N in both DW creep and flow regimes. To reveal the underlying mechanism of new findings, we performed further experiment and micromagnetic simulation, from which w…
Encapsulation of single-molecule magnets in carbon nanotubes
2011
Next-generation electronic, photonic or spintronic devices will be based on nanoscale functional units, such as quantum dots, isolated spin centres or single-molecule magnets. The key challenge is the coupling of the nanoscale units to the macroscopic world, which is essential for read and write purposes. Carbon nanotubes with one macroscopic and two nanoscopic dimensions provide an excellent means to achieve this coupling. Although the dimensions of nanotube internal cavities are suitable for hosting a wide range of different molecules, to our knowledge, no examples of molecular magnets inserted in nanotubes have been reported to date. Here we report the successful encapsulation of single-…
State of the Art in Alq3-Based Spintronic Devices
2015
Since the first observation of a magnetoresistance signal in a vertical organic spin valve in 2004, tris (8-hydroxyquinoline) aluminium (Alq3) molecule has become a standard material for organic spintronics devices. This chapter will briefly present the state of the art on Alq3-based spintronic devices and the different approaches applied through the years to try to optimize these systems. It will be remarked that, despite extensively investigated, many fundamental questions regarding the spin injection and transport mechanisms through the organic layer are still unclear. The chapter will also present some of the most controversial topics in the organic spintronic area and it will highlight…
Self-assembled monolayers on a ferromagnetic permalloy surface.
2015
Self-assembled monolayers (SAMs) are nowadays broadly used as surface protectors or modifiers and play a key role in many technological applications. This has motivated the study of their formation in all kind of materials; however, and despite the current interest in molecular spintronics, the study of SAMs on ferromagnetic surfaces remains almost unexplored. In this paper, we report for the first time a methodology for the formation of SAMs of n-alkylphosphonic acids on permalloy in ambient conditions. The formed monolayers have been fully characterized by means of contact angle measurements, atomic force microscopy, X-ray photoelectron spectroscopy, matrix assisted laser desorption ioniz…
Tuning Spin Current Injection at Ferromagnet-Nonmagnet Interfaces by Molecular Design.
2020
There is a growing interest in utilizing the distinctive material properties of organic semiconductors for spintronic applications. Here, we explore the injection of pure spin current from Permalloy into a small molecule system based on dinaphtho[2,3-b:2,3-f]thieno[3,2-b]thiophene (DNTT) at ferromagnetic resonance. The unique tunability of organic materials by molecular design allows us to study the impact of interfacial properties on the spin injection efficiency systematically. We show that both the spin injection efficiency at the interface and the spin diffusion length can be tuned sensitively by the interfacial molecular structure and side chain substitution of the molecule.
Long-distance spin-transport across the Morin phase transition up to room temperature in ultra-low damping single crystals of the antiferromagnet α-F…
2020
Antiferromagnetic materials can host spin-waves with polarizations ranging from circular to linear depending on their magnetic anisotropies. Until now, only easy-axis anisotropy antiferromagnets with circularly polarized spin-waves were reported to carry spin-information over long distances of micrometers. In this article, we report long-distance spin-transport in the easy-plane canted antiferromagnetic phase of hematite and at room temperature, where the linearly polarized magnons are not intuitively expected to carry spin. We demonstrate that the spin-transport signal decreases continuously through the easy-axis to easy-plane Morin transition, and persists in the easy-plane phase through …
Spin transport across antiferromagnets induced by the spin Seebeck effect
2018
For prospective spintronics devices based on the propagation of pure spin currents, antiferromagnets are an interesting class of materials that potentially entail a number of advantages as compared to ferromagnets. Here, we present a detailed theoretical study of magnonic spin current transport in ferromagnetic-antiferromagnetic multilayers by using atomistic spin dynamics simulations. The relevant length scales of magnonic spin transport in antiferromagnets are determined. We demonstrate the transfer of angular momentum from a ferromagnet into an antiferromagnet due to the excitation of only one magnon branch in the antiferromagnet. As an experimental system, we ascertain the transport acr…