As CMOS technologies face challenges in dimensional and voltage scaling, the demand for novel logic devices has never been greater, with spin-based devices offering scaling potential, at the cost of significantly high switching energies. Alternatively, magnetoelectric materials are predicted to enable low-power magnetization control, a solution with limited device-level results. Here, we demonstrate voltage-based magnetization switching and reading in nanodevices at room temperature, enabled by exchange coupling between multiferroic BiFeO 3 and ferromagnetic CoFe, for writing, and spin-to-charge current conversion between CoFe and Pt, for reading. We show that, upon the electrical switching of the BiFeO 3 , the magnetization of the CoFe can be reversed, giving rise to different voltage outputs. Through additional microscopy techniques, magnetization reversal is linked with the polarization state and antiferromagnetic cycloid propagation direction in the BiFeO 3 . This study constitutes the building block for magnetoelectric spin-orbit logic, opening a new avenue for low-power beyond-CMOS technologies.

Spin-orbitronic devices can integrate memory and logic by exploiting spin-charge interconversion (SCI), which is optimized by design and materials selection. In these devices, interfaces are crucial elements as they can prohibit or promote spin flow in a device as well as possess spin-orbit coupling resulting in interfacial SCI. Therefore, investigation of interfaces in spin-orbitronic devices is important. Here, we study the origin of SCI in a Py/Cu/W lateral spin valve and quantify its efficiency. An exhaustive characterization of the interface between Cu and W electrodes uncovers the presence of an oxidized layer (WOx). We determine that the SCI occurs at the Cu/WOx interface with a temperature-independent interfacial spin-loss conductance of G(broken vertical bar broken vertical bar) approximate to 20 x 10(13) Omega(-1) m(-2) and an interfacial spin-charge conductivity sigma(SC) = -1600 Omega(-1)cm(-1) at 10 K (-800 Omega(-1) cm(-1) at 300 K). This corresponds to an efficiency given by the inverse Edelstein length lambda(IEE) = -0.8 nm at 10 K (-0.4 nm at 300 K), which is remarkably larger than in metal/metal and metal/oxide interfaces and bulk heavy metals. The large SCI efficiency at such an oxidized interface makes it a promising candidate for the magnetic readout in MESO logic devices.

With the deceleration of dimensional and voltage scaling in CMOS technologies, the demand for novel logic devices has never been greater. While spin-based devices present a major opportunity towards favorable scaling, switching energies are still orders of magnitude above the expected values. Alternatively, magnetoelectric materials are predicted to enable low-power control of magnetization, a relatively unexplored pathway with sparse results at a device level. Here, we demonstrate voltage-based magnetization switching and reading in nanodevices at room temperature, enabled by exchange coupling between multiferroic BiFeO$_3$ and ferromagnetic CoFe, for the writing, and spin-to-charge current conversion between CoFe and Pt, for the reading. Unlike other current-based spintronic devices, magnetization writing is driven solely by voltage pulses. We show that, upon electrical switching of the BiFeO$_3$, the magnetization of the CoFe can be reversed, giving rise to different voltage outputs. The voltage-induced switching is supported through a combination of piezoresponse, magnetic force microscopy, and scanning nitrogen-vacancy magnetometry, where magnetization reversal is linked with the polarization state and antiferromagnetic cycloid propagation direction in the BiFeO$_3$. This study constitutes the building block for magnetoelectric spin-orbit logic, as well as a new avenue for low-power beyond-CMOS technologies.

Topological materials are of high interest due to the promise to obtain low power and fast memory devices based on efficient spin-orbit torque switching or spin-orbit magnetic state read-out. In particular, sputtered polycrystalline Bi_xSe_1-x is one of the materials with more potential for this purpose since it is relatively easy to fabricate and has been reported to have a very high spin Hall angle. We study the spin-to-charge conversion in Bi_xSe_1-x using the spin pumping technique coming from the ferromagnetic resonance in a contiguous permalloy thin film. We put a special emphasis on the interfacial properties of the system. Our results show that the spin Hall angle of Bi_xSe_1-x has an opposite sign to the one of Pt. The charge current arising from the spin-to-charge conversion is, in contrast, lower than Pt by more than one order of magnitude. We ascribe this to the interdiffusion of Bi_xSe_1-x and permalloy and the changes in chemical composition produced by this effect, which is an intrinsic characteristic of the system and is not considered in many other studies.

The development of spin-orbitronic devices, such as magnetoelectric spin-orbit logic devices, calls for materials with a high resistivity and a high spin-charge interconversion efficiency. One of the most promising candidates in this regard is sputtered BixSe1-x. Although there are several techniques to quantify spin-charge interconversion, reported values to date for sputtered BixSe1-x have often been overestimated due to spurious effects related to local currents combined with a lack of understanding of the effect of the interfaces and the use of approximations for unknown parameters, such as the spin diffusion length. In the present study, nonlocal spin valves are used to inject pure spin currents into BixSe1-x, allowing us to directly obtain its spin diffusion length as well as its spin Hall angle, from 10 K up to 300 K. These values, which are more accurate than those previously reported in sputtered BixSe1-x, evidence that the efficiency of this material is not exceptional. Indeed, the figure of merit for spin-charge interconversion, given by the product of these two parameters, is slightly under 1 nm. Our work demonstrates the importance of considering all material parameters and interfaces when quantifying the spin transport properties of materials with strong spin-orbit coupling.

One of the major obstacles to realizing spintronic devices such as MESO logic devices is the small signal magnitude used for magnetization readout, making it important to find materials with high spin-to-charge conversion efficiency. Although intermixing at the junction of two materials is a widely occurring phenomenon, its influence on material characterization and the estimation of spin-to-charge conversion efficiencies are easily neglected or underestimated. Here, we demonstrate all-electrical spin-to-charge conversion in BixSe1-x nanodevices and show how the conversion efficiency can be overestimated by tens of times depending on the adjacent metal used as a contact. We attribute this to the intermixing-induced compositional change and the properties of a polycrystal that lead to drastic changes in resistivity and spin Hall angle. Strategies to improve the spin-to-charge conversion signal in similar structures for functional devices are discussed.

We present the first experimental realization of a magnetoelectric spin-orbit (MESO) logic device at room temperature. Two logic states are determined by the magnetization direction of a nanostructured CoFe element, which is switched by a magnetoelectric BiFeO3 layer (WRITE) and detected through spin-to-charge conversion effect in a Pt element (READ).

This paper studies the phenomenon of mixed ionic and electronic conductivity in magnetron sputtered gadolinia doped ceria thin films under the effect of an applied DC bias. Electrochemical impedance spectroscopy was used to measure the change in impedance under an alternating voltage of 300 mV, at temperatures between 25 degrees C and 150 degrees C and applied biases of similar to 4-20 kV/mm, which are much higher than any prior study. The application of a DC bias produces a reversible decrease in both the grain and grain boundary resistances for GDC, and the films exhibit bias- induced mixed ionic and electronic conductivity. Additional features become visible in the Nyquist plots, indicating possible novel mechanisms in response to bias. Particularly interesting is the appearance of inductive loops in the low frequency regime, at very high bias values, rarely seen for such materials. Here this novel behavior was analyzed by fitting the data using equivalent circuits to understand the underlying mechanisms at play. Through this work, it is established that the change in behavior is attributed to electronic conduction through grain boundaries along the direction of the applied field. (c) 2019 Elsevier Ltd. All rights reserved.

HfO2 thin films were grown on Pt/TiO2/SiO2/Si substrates via RF magnetron sputtering technique at pure oxygen atmosphere with a substrate temperature of 550 °C. We studied the structural and electrical properties on HfO2 thin films, varying the thickness (tHfO2) from 23 to 155 nm. Grazing-incident x-ray diffraction shows a polycrystalline composition, some peaks are shifted when the tHfO2 increase, that is, a relaxation occur on the film. We fabricated In/HfO2/Ptlike a capacitor structurefor perform the electrical property measurements. The current-voltage curves display a resistive switching behavior for all thicknesses, and the resistance dependence with time, displays retention states with Low and High resistance in all samples. The percentage of change on resistance ([(RON-ROFF)/ROFF]×100) scale with HfO2 thickness and reach a saturation value ∼ 30% at tHfO2>120 nm.

We studied the voltage-induced resistive switching (RS) in ferroelectric/metal (BiFeO3/Nb:SrTiO3) vertical devices. We found switching with R-ON and R-OFF ratios of Delta R = 1-R-ON/R-OFF = 0.82 at voltages starting at V-SET, (RESET) = +/- 2 V. Upon increasing voltage, Delta R also increases until dielectric breakdown is reached. Interestingly, the V-SET, (RESET) values at which the RS becomes significant, coincides with the coercive voltage of the ferroelectric polarization, as measured by piezoelectric force microscopy in similar BiFeO3 films. This suggests that the driving mechanism of the RS effect in our films is connected to the BiFeO3 ferroelectricity. However, the increase of the RS effect after complete ferroelectric saturation points to an additional mechanism that may be related to vacancy displacements. This is further supported by forming process necessary to induce resistance bi-stability, typical of an RS effect.

The La2/3Sr1/3MnO3 (LSMO) with Curie temperature above room temperature is the leading compound of the manganite perovskite family. Therefore, the physical properties are desirable for practical applications as magnetic sensors. However, when the dimensions are reduced the ferromagnetic properties of material are weakened. In this research, we have grown La2/3Sr1/3MnO3/SrTiO3 thin films by sputtering DC at high oxygen pressure at 830 degrees C. X-Ray Diffraction (XRD) analysis reveals that only (0 0 2) LSMO peak are present, indicating a textured growth. The samples morphology was characterized by Atomic Force Microscopy (AFM). Additionally, LSMO microwires were patterned by UV lithography; the devices are a well-defined channel with current and voltage leads enabling four points resistance measurements. Resistivity versus temperature curves displays typical manganite behaviour with metal-insulator transition similar to 350K. We study the electric and magnetotransport properties in LSMO film and in wire channel and their dependence with size (width and length) for potential applications like magnetic sensors.

Se formularon cementos oseos modificados, empleando un co-monomero alcalino y Quitosano como carga bioactiva. Se efectuaron ensayos de caracterizacion fisico-quimica, termica y mecanica siguiendo la norma ISO 5833. Mediante el empleo de un diseno de experimentos de superficie de respuesta, se optimizo la composicion del cemento y se complemento el estudio con pruebas en condiciones in vitro por inmersion del material en un fluido biologico simulado e in vivo utilizando el cemento para fijar vastagos de titanio en el canal medular del femur izquierdo de bio-modelos (conejos)