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Resistive switching (RS) devices, often referred to as memristors, have exhibited interesting electronic performance that could be useful to enhance the capabilities of multiple types of integrated circuits that we use in our daily lives. However, RS devices still do not fulfil the reliability requirements of most commercial applications, mainly because the switching and failure mechanisms are still not fully understood. Density functional theory (DFT) and/or molecular dynamics (MD) are simulations used to describe complex interactions between groups of atoms, and they can be employed to clarify which physical, chemical, thermal and/or electronic phenomena take place during the normal operation of RS devices, which should help to enhance their performance and reliability. In this article, we review which studies have employed DFT and/or MD in the field of RS research, focusing on which methods have been employed and which material properties have been calculated. The goal of this article is not to delve into deep mathematical and computational issues – although some fundamental knowledge is presented – but to describe which type of simulations have been carried out and why they are useful in the field of RS research. This article helps to bridge the gap between the vast group of experimentalists working in the field of RS and computational scientists developing DFT and/or MD simulations. [ABSTRACT FROM AUTHOR]

The current study aims to introduce a new generalized photothermal model in which heat equation is described based on the Moore–Gibson–Thompson (MGT) equation. The thermo-optical transition process can be understood, and the interaction between elastic plasma waves and heat can be investigated and explained using the suggested model. The proposed model was used to investigate the thermal and photoacoustic effects in an infinitely constrained solid cylinder of semiconductor material that was crossed into a fixed magnetic field and subjected to a high-intensity laser heal flux. The Laplace transform technique is used to derive the numerical expressions for the components of thermal stresses, displacement, temperature field, and carrier density. The propagation of thermal, elastic, and plasma waves, as well as the distributions of each studied field, was investigated and described. The comparison is also used to evaluate the impact of thermoelastic response characteristics such as thermal relaxations, temperature frequency, and lifetime on the photo-thermoelastic response. [ABSTRACT FROM AUTHOR]

CoFe2NiMn0.3Alx (x = 0.25, 0.50, 0.75, 1.00) alloys were prepared using the arc melting method, and their crystal structure, microstructure, and mechanical properties were systematically studied. The results show that a greater Al content beneficially alters the crystal structure of the alloys from a single FCC phase to a mixture of FCC + BCC phases. With increasing Al content, the volume fraction of the BCC phase increases steadily, whereas the volume fraction of the FCC phase substantially decreases. With increasing Al content, the yield strength and hardness of the CoFe2NiMn0.3Alx alloys increases, whereas their ductility gradually decreases. Among the studied alloys, that with x = 0.75 exhibits both high strength and good ductility and its yield strength, fracture strength, and fracture strain are 1100 MPa, 2335 MPa, and 33.24%, respectively. Measurements of magnetic properties indicated that the saturation magnetization increases from 90 emu g−1 for the Al0.25 alloy to 148 emu g−1 for the Al1.00 alloy. The results show that the CoFe2NiMn0.3Alx high-entropy alloys are potential candidates to serve as magnetic materials in industrial applications. [ABSTRACT FROM AUTHOR]

CoZr columnar structured magnetic films were fabricated by oblique sputtering onto porous aluminum oxide substrates with different oblique angles. The scanning electron microscope images showed the formation of columnar structure and nanoporous structure was disappeared with increasing oblique angle. The static magnetic properties showed larger coercivity and lower magnetization squareness due to columnar structure resulted from nanopores. Dynamic magnetic properties were determined by effect of holes and oblique sputtering. Enhanced microwave absorption was obtained by complex permeability measurement, which line width of columnar film increased 1.4 GHz comparing with 0.5 GHz of continuous film. Therefore, it is an effective way to get the adjustable anisotropy field and line width, which is desirable for obtaining the high resonance and high permeability ferromagnetic film materials for high frequency application. [ABSTRACT FROM AUTHOR]

In the fabrication of bit-patterned media (BPM), two processes are commonly used, i.e., the pattern transfer by ion-milling into an underlying film of magnetic material, and the direct deposition of the magnetic material onto a pre-patterned substrate. We experimentally compared the switching performance of the BPM based on Co/Pd multilayers fabricated using these methods in terms of their switching field distribution (SFD) and physical characteristics of the bits. Our results show that both methods resulted in a narrow (∼15%) SFD at low areal recording densities of ∼0.15 Tdot/in2. However, at higher densities of up to 0.6 Tdot/in2, the SFD of the ion-milled samples detrimentally broadened to ∼30% while the BPM from the direct-deposition method maintained its narrow SFD up to a high bit density of 0.6 Tdot/in2. Our results suggest that in Co/Pd multilayer systems, the direct-deposition method, which produces more uniform bit sizes and profiles especially at high bit densities, is a more promising approach to achieving high-density BPM. [ABSTRACT FROM AUTHOR]

We study, using finite temperature Monte Carlo simulations, the demagnetization curves, coercivity, and energy product of multilayers of hard (Nd2Fe14B) and soft (FeCo) magnetic material. The easy axes of the hard and soft phases are parallel to the layers. We perform simulations with and without the dipolar interaction, with periodic and free boundary conditions, and find a significant influence of the dipolar interaction on the coercivity and the energy product. [ABSTRACT FROM AUTHOR]

Hard magnetic L10-Fe51Pt49 thin films with out-of-plane texture and film thicknesses between 3 and 200 nm have been prepared on MgO(001) single crystalline substrates by co-sputtering and have been magnetically investigated by SQUID magnetometry at different temperatures ranging from 40 K up to the Curie temperature. The Curie temperature is found to be 660 K for film thicknesses down to 8 nm and decreases almost linearly for thinner films. For the whole ferromagnetic temperature range the intrinsic magnetic material parameters (saturation polarization Js, magnetocrystalline anisotropy constant K1, exchange constant A) and the coercivity μ0Hc are determined as a function of the film thickness. Furthermore the microstructural parameters are ascertained by analyzing the temperature dependence of the coercivity within the framework of micromagnetism leading to a deeper understanding of the magnetic reversal process. [ABSTRACT FROM AUTHOR]

The atomically thin nature of two-dimensional (2D) materials allows the sufficient interactions between 2D materials and electric fields, enabling rich electrically tunable physical properties and novel device applications. • Two-dimensional (2D) materials possess rich electrically tunable electronic, optical, and magnetic properties. • Electrically tunable bandgap, valley valve, and excitons are reviewed in bilayer graphene. • Electrically tunable bandgap, photodetector, and optical modulator are reviewed in black phosphorus. • Electrically tunable transport, valley, and ferroelectric properties are reviewed in transition metal dichalcogenides. • Electrically tunable magnetic properties are reviewed in emerging magnetic materials, including CrI 3 , Gr 2 Ge 2 Te 6 , and Fe 3 GeTe 2. Two-dimensional (2D) materials, with atomically thin van der Waals layered structure, exhibit both novel physical properties and promising applications in electronic, optoelectronic and energy-harvesting devices. Currently 2D material research has become one of the most exciting topics in physics, engineering and material communities due to the easy preparation processes, rich species and unique properties. Among all the unique properties of 2D materials, the ability to electrically tune the electronic, optical and even magnetic properties at a mild electrostatic doping offers us numerous possibilities for investigating electro-matter interactions and novel device applications. Here, we review the electrically tunable physical properties of several interesting 2D materials as well as the relevant applications on devices utilizing these unique properties. The electrically tunable valley properties of 2D materials and the recent discovered 2D magnetism are also included. [ABSTRACT FROM AUTHOR]

Bioengineered spider silk is a biomaterial that has exquisite mechanical properties, biocompatibility, and biodegradability. Iron oxide nanoparticles can be applied for the detection and analysis of biomolecules, target drug delivery, as MRI contrast agents and as therapeutic agents for hyperthermia-based cancer treatments. In this study, we investigated three bioengineered silks, MS1, MS2 and EMS2, and their potential to form a composite material with magnetic iron oxide nanoparticles (IONPs). The presence of IONPs did not impede the self-assembly properties of MS1, MS2, and EMS2 silks, and spheres formed. The EMS2 spheres had the highest content of IONPs, and the presence of magnetite IONPs in these carriers was confirmed by several methods such as SEM, EDXS, SQUID, MIP-OES and zeta potential measurement. The interaction of EMS2 and IONPs did not modify the superparamagnetic properties of the IONPs, but it influenced the secondary structure of the spheres. The composite particles exhibited a more than two-fold higher loading efficiency for doxorubicin than the plain EMS2 spheres. For both the EMS2 and EMS2/IONP spheres, the drug revealed a pH-dependent release profile with advantageous kinetics for carriers made of the composite material. The composite spheres can be potentially applied for a combined cancer treatment via hyperthermia and drug delivery. [ABSTRACT FROM AUTHOR]

Highlights • A method to measure nanocrystalline samples crystalline fraction fc is presented. • Superparamagnetic transition temperature Ttr is used to determine fc. • The Ttr crystalline fraction dependency is modelled. • The intergrain dipolar coupling an interphase exchange coupling are considered. • Experimental measurement have beeb carried out and are presented. [ABSTRACT FROM AUTHOR]

The performance of microwave devices mainly depends on the properties of materials used in the fabrication. Knowledge of material properties at microwave frequencies is a prerequisite to select suitable materials for various microwave applications and vice versa. In this review, seven categories of materials and their applications in a microwave regime are elaborately discussed. The categories include magnetic materials, carbon-based materials, flexible or stretchable materials, biomaterials, phantoms, tunable materials and metamaterials. A brief overview of other important microwave materials such as low-loss ceramic dielectric materials, low-loss polymer ceramic composites, glass ceramics and multilayer ceramics is also given. The objective of this review is to expose the world of materials for wide microwave applications and thereby properly assisting the material selection for specific applications. Moreover, this review has dual significance. It helps material scientists to develop new materials and modify the properties of the available materials with respect to the application requirements. It also assists microwave engineers to select and use appropriate materials for different microwave applications. [ABSTRACT FROM AUTHOR]

The method of evaluating the magnetocaloric effect (MCE) and heat capacity of various magnetic samples from calorimetric experiments are presented. This method allows determining the MCE of the magnetic solid samples of indefinite shape, the MCE of microparticles in suspensions and the MCE of magnetic nanoparticles in the colloids. The method was tested on a gadolinium metal, which has one of the biggest values of MCE at room temperature. The observed data, compared with other experimental works, are in a good agreement, and it confirms the practicality of this method. [ABSTRACT FROM AUTHOR]

Two media, A and B, are discussed to illustrate the media requirements and properties for the 230 Gb/in2 demonstration. A and B had similar layer structures except that the recording layers had different oxide compositions and that the exchange break layer thicknesses were 21 and 13 nm, respectively. They had similar coercivity and intrinsic switching field but showed large difference in writability. Consequently, even though they achieved similar performance for heads down to a track width of 150 nm, medium A could not be saturated adequately for heads with a track width of 120 nm. On the other hand, medium B possessed the desirable properties for high density recording and formed the base for the media that were used in the 230 Gb/in2 demonstration. [ABSTRACT FROM AUTHOR]

Two media, A and B, are discussed to illustrate the media requirements and properties for the 230 Gb/in2 demonstration. A and B had similar layer structures except that the recording layers had different oxide compositions and that the exchange break layer thicknesses were 21 and 13 nm, respectively. They had similar coercivity and intrinsic switching field but showed large difference in writability. Consequently, even though they achieved similar performance for heads down to a track width of 150 nm, medium A could not be saturated adequately for heads with a track width of 120 nm. On the other hand, medium B possessed the desirable properties for high density recording and formed the base for the media that were used in the 230 Gb/in2 demonstration. [ABSTRACT FROM AUTHOR]