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In this paper, we investigate the switch of a magnet-based superconducting spin valve. As a magnet, we consider the MnSi compound characterized by a complex magnetic structure with its magnetization in the form of a spiral helicoid. A model is given for a double-layered superconducting spin valve based on the spiral magnet with an adjoining superconducting thin layer. As shown previously, critical temperature of such a superconducting film depends on the direction of the spiral magnet. Calculations have been performed for magnetic dynamics of this structure, which in prospect can serve as the basis for creating memory or logic elements of low temperature nanoelectronics. Several problems have been treated with regards to mathematical simulation of switching the spin valve magnetization, research on the spin valve structure using electromagnetic simulation software to change magnetization and rotation of the spiral magnetic vector under the magnetic-field pulse, construction and analysis of 3D magnetization distributions in spiral magnets to trace the process of remagnetization. In this work, we use a Matlab-based software environment and tools for constructing distribution plots of vector fields. It is shown that the direction of the spiral magnet can be switch by pulsed magnetic field. Research has been done on the resultant magnetization distributions visualized in the form of vector fields.

As the need for ever greater transistor density increases, the commensurate decrease in device size approaches the atomic limit, leading to increased energy loss and leakage currents, reducing energy efficiencies. Alternative state variables, such as electronic spin rather than electronic charge, have the potential to enable more energy-efficient and higher performance devices. These spintronic devices require materials capable of efficiently harnessing the electron spin. Here we show robust spin transport in Cd3As2 films up to room temperature. We demonstrate a nonlocal spin valve switch from this material, as well as inverse spin Hall effect measurements yielding spin Hall angles as high as θSH = 1.5 and spin diffusion lengths of 10-40 μm. Long spin-coherence lengths with efficient charge-to-spin conversion rates and coherent spin transport up to room temperature, as we show here in Cd3As2, are enabling steps toward realizing actual spintronic devices.

In this article, we provide an initial qualitative description of the basic magnetization reversal processes behind temperature and cooling field-dependent exchange bias effect at Co/CoO interface of Fe3O4/Alq3/Co/CoO/Au hybrid spin valve (SV) device structure. The exchange field at Co/CoO interface is observed to be inversely proportional to temperature, indicating enhanced magnetic field sensitivity of Co reverse domain nucleation at the high-temperature region. The exchange field, at constant temperature, is found to be insensitive to change in the cooling field, which may be due to efficient ferromagnetic coupling at the Co/CoO interface of the device. Sudden decrease of exchange field with training cycle number ( $n$ ) has been observed at lower values of $n$ , which may be attributed to rearrangement of Co pinned layer spin configuration toward equilibrium. Interestingly, incorporation of antiferromagnetic CoO layer has not been observed to bring any change in magnetoresistance (MR) behavior of the exchange biased SV device, which shows a two-step switching pattern of MR at 100 K.

In the last decade, two-dimensional (2D) transition metal dichalcogenides have been introduced with great significance in the spintronic devices for their extraordinary electrical, optical, and spin-dependent properties. In this work, we have fabricated a few-layer molybdenum disulfide (FL-MoS2) (~6 nm) as a non-magnetic spacer layer in Ni–Mn–In/FL-MoS2/Ni–Mn–In magnetic tunnel junction (MTJ) using DC magnetron sputtering. FL-MoS2 thin film sandwiched between two ferromagnetic shape memory alloy based electrodes exhibit semiconducting behavior, confirmed by current-voltage (I–V) characteristics and temperature dependent resistance measurement. The fabricated MTJ shows spin valve effect in the presence of an external magnetic field. The tunneling magnetoresistance (TMR) has been recorded in 10 K–300 K temperature range. The highest TMR ratio of 0.51% was obtained at a low temperature ~10 K, corresponding to the spin polarization of ~5%. This TMR ratio reduces to a value of 0.032% as the temperature of the device increases up to 300 K, displaying a finite TMR at room temperature. A detailed study of thickness and temperature-dependent magnetization versus magnetic field (M − H) hysteresis loops of Ni–Mn–In thin films has been performed to understand the complex TMR behavior. The present study paves the way for the use of sputtered FL-MoS2 and ferromagnetic shape memory alloy in ultrafast spintronics for advanced magnetic devices application.

Organic spin valve (OSV), one of the most promising and representative devices involving spin injection, transport and detection, has drawn tremendous attention owing to their ultra-long spin relaxation time in the field of molecular spintronics. Since the first demonstration of truly worked vertical OSV device in 2004, efforts in enhancement of high performance and pursuit of spin-related nature have been devoted in related field. It offers a new opportunity to develop the integrated flexible multi-functional arrays based on spintronics in the future. However, the unreliable working state in OSVs due to the lack of exploration on interface control will cause severe impact on the performance evaluation and further restrict their practical application. Herein, we focus on the recent progress in strategies for reliable fabrication and evaluation of typical OSVs in vertical configuration. Firstly, the challenges in protection of two spin interface properties and identification of spin-valve-like signals were proposed. Then, three points for attention including selection of bottom electrodes, optimization of organic spacer, and prevention of metal penetration to improve the device performance and reliability were mentioned. Particularly, various modified strategies to solve the “dead layer” issue were highlighted. Furthermore, we discussed the general protocols in the reliable evaluation of OSVs’ performance and transport mechanism identification. Notably, several key fundamentals resulting in spurious magnetoresistance (MR) response were illustrated. Finally, we also highlighted the future perspectives on spintronic devices of organic materials.

International audience; In the field of spintronics, there are many reasons to use molecular tunnel barriers in devices such as low cost, flexibility and long spin life time in organic materials [1, 2]. What happens at the interfaces in these organic-inorganic hybrid systems is so relevant to the properties that a word has been proposed for it: spinterface [3]. The discrete nature of the molecular levels explains the variation of the magneto-transport properties with respect to the type of molecules and the nature of the interfaces [4]. To investigate such spinterface issues there is a need for very well-defined interfaces, which can be obtained in ultra-high vacuum conditions (UHV).The aim of this work is to realize model hybrid hetero-structures with a molecular monolayer as tunnel barrier between two ferromagnetic layers (spin valve). Modifying the way molecules are linked to the substrate, the crystallographic orientation of the substrate and the nature of the molecules are possible ways to modify the system spinterfaces. In this study, the grafting under UHV of the molecular layer (1-hexadecanethiol molecules, noted C16MT) on epitaxial ferromagnetic Fe (001) electrodes has been studied using scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). To avoid the formation of pinholes during deposition of the Co ferromagnetic top electrode of the spin-valve, an original soft-landing technique has been used, based on the condensation at low temperature of a Xe layer on the self-assembled monolayer before metal deposition. The electrical homogeneity of the obtained junctions has been controlled from the micro to the nanoscale by Ballistic Electron Emission Microscopy (BEEM) [5]. Investigation of the magnetotransport properties of these model spin- valves is in progress and will be confronted to the precise analysis of the system bottom spinterface by spin-resolved IPES (Inverse PhotoEmission Spectroscopy).References:[1] J. R. Petta, S. K. Slater, et al., Physical Review Letters, 93, 136601, 2004. [2] S. Sanvito, Chemical Society Reviews, 40, 3336-3355, 2011.[3] S. Sanvito, Natur Physics, 6, 562-564, 2010.[4] M. Galbiati, S. Tatay, et al., Applied Physics Letters, 106, 082408, 2015. [5] A. Junay, S. Guézo, et al., Journal of Applied Physics, 118, 085310, 2015.

The Monte Carlo study of spin-valve magnetic structures with giant magnetoresistance effects has been performed with the application of the Heisenberg anisotropic model to the description of the magnetic properties of ultrathin ferromagnetic films. The dependences of the magnetic characteristics on the temperature and external magnetic field have been obtained. Dependence of hysteresis phenomena on thickness of ferromagnetic films and various values of intralayer and interlayer exchange interaction is studied.

The Monte Carlo simulation of magnetic properties of spin-valve sandwich structures, where ultrathin ferromagnetic films divided by layer of nonmagnetic metal, and antiferromagnetic, are coupled antiferromagnetically, is realized. The anisotropic Heisenberg model is applied for description of magnetic properties. Dependence of hysteresis phenomena on thickness of ferromagnetic films and various values of interlayer exchange interaction is revealed.

The paper considers the modeling of a multilayer nanocomposite, the combination of elements of which gives rise to a spin valve effect. The relevance and importance of effects in the field of spintronics and related materials and devices are described. We study the composition and atomic structure of individual layers of a multilayer nanocomposite, as well as the composition and morphology of the interface of nanocomposite layers. We analyzed a sample with a periodic superconductor-ferromagnet structure consisting of more than 20 alternating layers of niobium and cobalt. The deposition process took place in a deep vacuum. The simulation was carried out by the molecular dynamics method using the potential of the modified immersed atom method. The formation of layers was carried out in a stationary mode. The temperature was adjusted using the Nose-Hoover thermostat. The deposition of each nanofilm ended with a relaxation stage for the necessary stabilization and restructuring of the formed nanocomposite. Three deposition temperature regimes were considered: 300 K, 500 K, and 800 K. For these modes, we analysed the atomic structure of nanofilms and transition regions (interface) formed between the layers. A study of the atomic structure of nanofilms showed that niobium is formed by crystalline regions of different orientations. A cobalt nanofilm is characterized by a structure close to amorphous. The structural features of the interface between the superconductor-ferromagnet layers largely depend on a relief of the surface onto which the deposition is made. The smallest variation in atomic composition is observed in the first niobium-cobalt contact zone, since the formation of the first nanofilm occurs on an even plane of the substrate. An analysis of the influence of the temperature regime during the formation of the nanosystem shows the dependence of the processes of formation of multilayer nanofilm formation, the interface of nanolayers, as well as the composition and morphology of heterostructures on the temperature at which a nanocomposite is manufactured. An increased temperature leads to the formation of a more rarefied structure of nanolayers and an increase in the zones of the interface of nanolayers due to the diffusion of atoms of the sprayed materials.

The van der Waals (vdW) materials offer an opportunity to build all-two-dimensional (all-2D) spintronic devices with high-quality interfaces regardless of the lattice mismatch. Here, we report on an all-2D vertical spin valve that combines a typical layered semiconductor MoS2 with vdW ferromagnetic metal Fe3GeTe2 (FGT) flakes. The linear current-voltage curves illustrate that Ohmic contacts are formed in FGT/MoS2 interfaces, while the temperature dependence of the junction resistance further demonstrates that the MoS2 interlayer acts as a conducting layer instead of a tunneling layer. In addition, the magnitude of the magnetoresistance (MR) of 3.1% at 10 K is observed, which is around 8 times larger than that of the reported spin valves based on MoS2 sandwiched by conventional ferromagnetic electrodes. The MR decreasing monotonically with increasing temperature follows the Bloch's law. As the bias current decreases exponentially, the MR increases linearly up to a maximum value of 4.1%. Our results reveal the potential opportunities of vdW heterostructures for developing novel spintronic devices.

We present both theoretical and experimental investigations of the proximity effect in a stack-like superconductor/ferromagnetic (S/F) superlattice, where ferromagnetic layers with different thicknesses and coercive fields are made of Co. Calculations based on the Usadel equations allow us to find the conditions at which switching from the parallel to the antiparallel alignment of the neighboring F-layers leads to a significant change of the superconducting order parameter in superconductive thin films. We experimentally study the transport properties of a lithographically patterned Nb/Co multilayer. We observe that the resistive transition of the multilayer structure has multiple steps, which we attribute to the transition of individual superconductive layers with the critical temperature, Tc, depending on the local magnetization orientation of the neighboring F-layers. We argue that such superlattices can be used as tunable kinetic inductors designed for artificial neural networks representing the information in a “current domain”.

The dynamics of the magnetization vector of the free layer of a layered spin-valve structure has been simulated. As materials for a free and fixed layer, we have considered six magnetically soft ferromagnets with planar anisotropy. The types of magnetization dynamics being of practical interest for MRAM and HMDD (magnetization vector switching), STNO (stable precession of the magnetization vector), and the PSL base element (magnetization vector switching with two probable results) are allocated. The ranges of currents and fields corresponding to these operating modes of a spin valve are calculated. The numerical calculations of the switching time showed that of the materials considered, the most suitable for a MRAM cell is the Co80Gd20 alloy and Fe60Co20B20 for the HMDD reading head. As a result of calculating the frequency of precession, it was concluded that the Fe60Co20B20 alloy is optimal in manufacturing STNO ferromagnetic layers. For PSL implementation, the best switching characteristics were obtained for Co93Gd7 alloy.

The characteristics of MIS structures based on insulating PbSnTe:In films grown by molecular beam epitaxy (MBE) with compositions near the band inversion are studied. It is shown that a number of their features can be induced by a ferroelectric phase transition with the Curie temperature in the range of 15-20 K. The injection and detection of spin-polarized electrons in PbSnTe:In are studied by using ferromagnetic contacts Co and Co $${}_{40}$$ Fe $${}_{40}$$ B $${}_{20}$$ . A spin-valve effect is discovered by measuring the magnetoresistance in local geometry at a distance of more than 30 $$mu$$ m from ferromagnetic contacts. The presence of a surface spin-polarized state with a linear dispersion law is demonstrated by means of the photoemission with angular and spin resolution.