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Increasing the density of data storage is crucial to the future of inexpensive digital technology. The large majority of storage in the “Cloud” consists of magnetic hard-disk drives. The continued evolution of this USD$30 billion industry depends on the commercial introduction of heat-assisted magnetic recording (HAMR). This technology uses heat from a laser beam confined well below the diffraction limit, <50-nm wide, to write to media near 450°C with high magnetic anisotropy that would normally be unwriteable under available magnetic fields. This high anisotropy guarantees thermal stability even for grain sizes around 5-nm diameter, which are necessary for major increases in storage density. In this article and in the articles in this issue, we introduce HAMR requirements and discuss its numerous interdisciplinary materials challenges, including high-temperature/efficient plasmonic materials, low-loss optical materials, highly ordered/thermally anisotropic nanoscale magnetic grains, block copolymers for directed assembly below 10 nm, high-temperature nanometer-thick coatings/lubricants, materials/interfaces to control heat flow at nanometer length scales, and advanced spintronic materials. [ABSTRACT FROM PUBLISHER]

We report on the structural, mechanical, magneto-electronic and thermodynamic properties of cubic sodium based fluoro-perovskite NaXF3 (X $=$ V, Co) through density functional theory (DFT). The generalized gradient approximation of Perdew, Burke, and Ernzerh (GGA-PBE) and the Tran-Blaha modified Becke-Johnson potential (TB-mBJ) are used for modeling exchange-correlation effects. The calculated lattice parameters agree well with the experimental measurements. Elastic properties show that these compounds are mechanically stable. The results of spin-polarized band structure show a half metallic behavior of NaVF $_{3}$ and NaCoF $_{3}$ . The magnetic study shows that the nature of these compounds is ferromagnetic and the integer value of the total magnetic moment confirms the half metallicity for both materials. The thermodynamic characters are also investigated through quasi-harmonic approximation. [ABSTRACT FROM AUTHOR]

The rare earth elements are become emerging source of ferromagnetism in spinel chalcogenides which can open the new ways for spintronic industry. Therefore, here in this article, the electronic, ferromagnetic, and transport features of MgEr 2 (S/Se) 4 are studied systematically. The enthalpy of formation (ΔH) has been reported for assurance of thermodynamic existence and energy release during optimization in ferromagnetic state (FM) guarantee the magnetic stability. Curie temperature (T c) describes by Heisenberg through classical model. The spin polarization density, and band structures (BS) evaluation depict the ferromagnetism and complete spin polarization. The densities of states (DOS) are elaborated the role of p-d coupling in terms of exchange energies Δ x (pd) and Crystal field energy Δ CF. The exchange mechanism of electrons spin, and exchange constants are calculated to note the energy lowering in spin down which confirm the stable ferromagnetism. Furthermore, thermoelectric characteristics are evaluated for energy harvesting and their effect on electrons spin functionality. The large power factor, and ultralow thermal conductivity make them appealing for thermoelectric generators. [Display omitted] • The role rare earth elements in ferromagnetism, and spintronic applications. • Use of materials as magnesium ion battertties and energy storage. • The ferromagnetism by electron spin instead of magnetic ion clustering. • Half metallic ferromagnetism evidence 100% spin polarization. • Ultralow low thermal conductivity increases the impotance for device fabrication. [ABSTRACT FROM AUTHOR]

The graphane can realizes a perfect spin filtering by changing the hybridizations of the defective carbon atoms. The H-vacancy defects introduce a novel transport channel in the two-probe σ-bond graphane devices, providing by through-space interactions. [Display omitted] The electronic transport properties of H-vacancy-defected graphane are investigated by using the density functional theory (DFT) and Non-equilibrium Green's Function (NEGF) methods. Results show that the band gap of graphane depends on the relative positions of the defect bands introduced by H vacancies and the valence or conduction bands, suggesting the band gap controllability. The defect bands are obviously spin polarized and the ratio is almost 100%. And the magnetization of the system can be tuned by defect concentration and location. Moreover, in the two-probe systems, the presence of H-vacancy-defect bands near the E f plays an important role in controlling spin-dependent transport of graphane. A perfect spin-filtering effect with 100% spin polarization could be realized by H-vacancy defects. The spin properties indicate the potential of graphane as an option for future graphene-based spin filters and spintronic devices. [ABSTRACT FROM AUTHOR]

Current modulation and rectification is an important subject of electronics as well as spintronics. In this paper, an efficient rectifying mesoscopic device is introduced. The device is a two terminal device on the 2D plane of electron gas. The lateral contacts are half-metal ferromagnetic with antiparallel magnetizations and the central channel region is taken as ferromagnetic or normal in the presence of an applied magnetic field. The device functionality is based on the modification of spin-current by tuning the strength of the magnetic field or equivalently by the exchange coupling of the channel to the substrate. The result is that the (spin-) current depends on the polarity of the bias voltage. Converting an alternating bias voltage to direct current is the main achievement of this model device with an additional profit of rectified spin-current. We analyze the results in terms of the spin-dependent barrier in the channel. Detecting the strength of the magnetic field by spin polarization is also suggested. [ABSTRACT FROM AUTHOR]

The present investigation focuses on the structural properties and magnetic response of Co, Mn and Co-Mn doped TiO 2 nanoparticles (within 3% dilute doping) along with their optical and electrical studies. X-ray diffraction (XRD) patterns for all these samples show the formation of tetragonal TiO 2 anatase phase with no extra impurity phases. Further, Raman bands at 143 cm −1 , 396 cm −1 , 516 cm −1 and 639 cm −1 also confirm the anatase phase in these samples. Diamagnetic response has been observed in pure TiO 2 nanoparticles. However, room temperature (RT) ferromagnetism has been observed with Co and/or Mn doping which gets enhanced further with codoping of Co ions. The observed ferromagnetism has been attributed to the formation of shallow levels with doping/codoping. The Co and/or Mn-doped TiO 2 nanoparticles are referred as diluted magnetic semiconductors due to their combined semiconducting and ferromagnetic response. UV-Vis spectra show the band gap of these samples are in the range of 3.03 eV–3.24 eV and a reduction in band gap is observed after codoping. The temperature dependent electrical conductivity measurements also show an enhancement in conductivity after codoping at RT. [ABSTRACT FROM AUTHOR]

In this work, the electronic and magnetic properties of SnFeO spinel ferrite with various cation distributions (mixed, normal and inverse spinel phases) were studied. The calculations were performed by Korringa-Kohn-Rostoker (KKR)-coherent potential approximation (CPA) method with generalized gradient (GGA) approximation for the exchange and correlation functional. Our spin-polarized calculations give a half-metallic character for SnFeO inverse spinel phase and near half-metallic character for SnFeO mixed spinel phase and metal character for SnFeO normal spinel phase. These results, which contribute to understanding the effect of the cation distribution in SnFeO ferrite with spinel structure in the existence of gap states occupied by majority and minority spin electrons, the spin magnetic moments, the magnetization and the half-metallic behaviour. [ABSTRACT FROM AUTHOR]

The magnetic properties of FeO, with the presence of Fe and O vacancy atoms, were carried out using the KKR-CPA method in density functional theory (DFT) implemented in the MACHIKANYAMAv2009 package, by considering local density approximation (LDA) and local density approximation-self-interaction-correction (LDA-SIC) approximations. Our study presents total, atoms projected density of states (DOS), and magnetic moments of different atoms in FeO with and without vacancy atoms; we provide an atomic level insight for magnetite which is a necessary step to understand their electronic, half-metallicity, and magnetic properties. We also noticed that the half-metallic behaviors of FeO contribute to a better understanding of the utility of this material in spintronic applications. [ABSTRACT FROM AUTHOR]

The electronic structures and magnetic properties of CoMnTaSi and CoMnTaGe Heusler alloys with LiMgPbSb-type structure investigated firstly by using the first-principles calculations. We have applied the full-potential linearized augmented plane waves plus local orbitals (FP-L/APW+LO) method. Exchange-correlation effects are treated using the generalized gradient approximations GGA and GGA+ U. The GGA calculation shows the CoMnTaSi and CoMnTaGe compounds at its equilibrium lattice constant are HM ferromagnet with an indirect band gap Γ → X of 0.34 and 0.39 eV and a HM gap of 0.34 and 0.13 eV in the spin-down channel. The CoMnTaZ (Z = Si, Ge) compounds have an integer total magnetic moment of 1.00 μB, satisfying the Slater-Pauling rule mtot = ( Nv − 24). The similar results are also obtained by GGA+ U calculation. Therefore, these new materials are good candidates for potential applications in spintronic. [ABSTRACT FROM AUTHOR]

In this work, a study of the electronic and magnetic properties of SnFe 2 O 4 spinel ferrite for different case of octahedral and tetrahedral distribution was carried out by using the Full Potential Linearized Plane Wave (FP-LAPW) method in density functional theory (DFT) implemented in the WIEN2K package, with the generalized gradient (GGA) and Tran-Blaha modified Becke-Johnson approximations for the exchange and correlation functional. Our spin-polarized calculations based on mBJ correction show a half metallic behavior for SnFe 2 O 4 which confirm the usefulness of SnFe 2 O 4 in spintronic application. From the magnetic properties calculations, it is found that the magnetic moment per formula unit is 8.0327 µ β , 0.000015 µ β and 3.99µ β in SnFe 2 O 4 100% normal, 100% inverse and 50% inverse, respectively. [ABSTRACT FROM AUTHOR]

Ab-initio calculations are performed to examine the electronic structures and magnetic properties of spin-polarized Ga1-xMnxP (x = 0.03, 0.25, 0.5, and 0.75) ternary alloys. In order to perceive viable half-metallic (HM) states and unprecedented diluted magnetic semiconductors (DMSs) such as spintronic materials, the full potential linearized augmented plane wave method is utilized within the generalized gradient approximation (GGA). In order to tackle the correlation effects on 3d states of Mn atoms, we also employ the Hubbard U (GGA + U) technique to compute the magnetic properties of an Mn-doped GaP compound. We discuss the emerged global magnetic moments and the robustness of half-metallicity by varying the Mn composition in the GaP compound. Using GGA + U, the results of the density of states demonstrate that the incorporation of Mn develops a half-metallic state in the GaP compound with an engendered band gap at the Fermi level (EF) in the spin-down state. Accordingly, the half-metallic feature is produced through the hybridization of Mn-d and P-p orbitals. However, the half-metallic character is present at a low x composition with the GGA procedure. The produced magnetic state occurs in these materials, which is a consequence of the exchange interactions between the Mn-element and the host GaP system. For the considered alloys, we estimated the X-ray absorption spectra at the K edge of Mn. A thorough clarification of the pre-edge peaks is provided via the results of the theoretical absorption spectra. It is inferred that the valence state of Mn in Ga1-xMnxP alloys is +3. The predicted theoretical determinations surmise that the Mn-incorporated GaP semiconductor could inevitably be employed in spintronic devices. [ABSTRACT FROM AUTHOR]

In recent years, Spin-Transfer Torque Random Access Memory (STT-RAM) has attracted significant attentions from both industry and academia due to its attractive attributes such as small cell area and non-volatility. However, long switching time and large programming energy of Magnetic Tunneling Junction (MTJ) continue being major challenges in STT-RAM designs. In order to overcome this problem, a Giant Spin-Hall Effect (GSHE) assisted STT-RAM structure (GSHE-RAM) has been recently invented. In this work, we investigate logic gates by using GSHE MTJs and two possible GSHE-RAM designs from the aspects of two different write access operations, namely, High Density GSHE-RAM and Disturbance Free GSHE-RAM, respectively. In High Density GSHE-RAM, GSHE current is shared by the entire bit line. Such a structure removes the GSHE control transistor from each GSHE-RAM cell and hence, substantially reduces the memory cell area. In Disturbance Free GSHE-RAM, one memory cell contains two transistors to remove the disturbance to the unselected bits and eliminate the possible erroneous flipping of the bits. In addition to memory designs, we also investigate logic gates by using GSHE MTJs. By leveraging the benefit of greater power efficiency and area density, GSHE MTJ elements become a suitable candidate for spintronic logic gates. Compare with traditional MOS transistors based logic gates, GSHE MTJ based logic can operate as a non-volatile memory and requires a much smaller number of elements to perform same logical operations (i.e., ‘AND’, ‘OR’, ‘NAND’ or ‘NOR’ gate.). And compare with other spin based logics, GSHE MTJ based logic also provides an better performance, excellent CMOS process compatibility and great fan-out ability. [ABSTRACT FROM AUTHOR]

In this study, we demonstrate an original elaboration route for producing a Mn-doped Ge self-assembled quantum dots on SiO 2 thin layer for MOS structure. These magnetic quantum dots are elaborated using dewetting phenomenon at solid state by Ultra-High Vacuum (UHV) annealing at high temperature of an amorphous Ge:Mn (Mn: 40%) nanolayer deposed at very low temperature by high-precision Solid Source Molecular Beam Epitaxy on SiO 2 thin film. The size of quantum dots is controlled with nanometer scale precision by varying the nominal thickness of amorphous film initially deposed. The magnetic properties of the quantum-dots layer have been investigated by superconducting quantum interference device (SQUID) magnetometry. Atomic force microscopy (AFM), x-ray energy dispersive spectroscopy (XEDS) and transmission electron microscopy (TEM) were used to examine the nanostructure of these materials. Obtained results indicate that GeMn QDs are crystalline, monodisperse and exhibit a ferromagnetic behavior with a Curie temperature (TC) above room temperature. They could be integrated into spintronic technology. [ABSTRACT FROM AUTHOR]

The electronic structure and mechanical properties of some cobalt-based binary half-Heusler alloys Co2X (X = In, Si, Sb, Sn, Ga) have been investigated using the density functional theory approach. The site preference by cobalt and X is similar to the traditional half-Heusler structure. The results showed that Co2 Si is not a half-metal but rather an n-type degenerate semiconductor. The compounds Co2Ga, Co2Sb, and Co2Sn are thermodynamically unstable and Co2 In is elastically unstable. With much care given to the lattice size, half metallicity is readily predicted in Co2 In, Co2Ga, Co2Sn, and Co2Sb. All the compounds showed directional bonding and they should exhibit high strength. The trend is that the low valence main group elements are likely to form half metals more readily in a binary half-Heusler alloy than the high valence main group elements. [ABSTRACT FROM AUTHOR]

We report a theoretical study of electronic structures and magnetic properties of Fe-doped CdS (10-10) thin films using first principle calculations within the density functional theory. It is shown that Fe atoms occupying Cd sites prefer to reside on the surface and couple antiferromagnetically. However, our results show the existence of competition between ferromagnetic and antiferromagnetic coupling because of the smaller total energy difference. Moreover, our density of states shows the existence of a simultaneous hybridization between the Fe d and S p states near the Fermi level. [ABSTRACT FROM AUTHOR]

We study the effect of surface adsorption of 27 different adatoms on the electronic and magnetic properties of monolayer black phosphorus using density functional theory. Choosing a few representative elements from each group, ranging from alkali metals (group I) to halogens (group VII), we calculate the band structure, density of states, magnetic moment and effective mass for the energetically most stable location of the adatom on monolayer phosphorene. We predict that group I metals (Li, Na, K), and group III adatoms (Al, Ga, In) are effective in enhancing the n-type mobile carrier density, with group III adatoms resulting in lower effective mass of the electrons, and thus higher mobilities. Furthermore, we find that the adatoms of transition metals Ti and Fe produce a finite magnetic moment (1.87 and 2.31 μB) in monolayer phosphorene, with different band gap and electronic effective masses (and thus mobilities), which approximately differ by a factor of 10 for spin-up and spin-down electrons, opening up the possibility for exploring spintronic applications. [ABSTRACT FROM AUTHOR]

Current-induced domain wall (DW) motion in spintronic racetrack memory promises energy-efficient analog computation using compact magnetic nanowires. This paper explores the feasibility of analog-to-digital converter (ADC) based on current-induced DW motion and introduces an n-bit ADC using n racetrack magnetic nanowires. With each magnetic nanowire having a different configuration granularity, an n-bit binary or gray code is generated simultaneously. The proposed ADC structure achieves 21 fJ/conversion-step at 20 MHz with an area of about 10~\mu \textm^2 . The racetrack ADC is suitable for applications requiring dense ADC arrays, such as image sensors. This paper describes one ultrahigh speed digital pixel sensor imaging system benefiting from the racetrack ADC. [ABSTRACT FROM PUBLISHER]

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We present a quantum-mechanical first-principle calculation of the structural, elastic, electronic, and magnetic properties of the full-Heusler compounds TiNi X ( X= Al, Ga, and In). The calculation uses the full-potential linearized augmented plane waves plus local orbital method to describe Ti-based Heusler alloys. The results show that these compounds exhibit half metallic characteristics over a wide range of mesh parameters and obey the Slater-Pauling rule, which states that the total magnetic moment per unit cell M = Z − 18 for half-Heusler compounds XYZ and M = Z − 24 for full-Heusler X YZ compounds. For these new alloys TiNi X ( X= Al, Ga, and In), we initially considered the two possible L2 structures AlCuMn and CuHgTi. However, two subsequent structural studies showed that only the CuHgTi-like structure is half metallic. Over a wide range of mesh parameters, the calculations give a total magnetic moment of 3.00 μ . These results suggest that TiNi X ( X= Al, Ga, and In) are promising materials for spintronic applications. [ABSTRACT FROM AUTHOR]

Between the ferromagnetic semiconductors of the III-V group, the transition metals (TMs) doped aluminum nitride (Al, TM)N diluted magnetic semiconductor (DMS) is the most well understood and promising applications in spintronic, due to its high Curie temperature. In this research, electronic and magnetic properties of pure armchair (4, 4) and zigzag (6,0) aluminum nitride Nanosheets (AlNNS) and doped with transition metals are investigated using the spin-polarized density functional theory. The spin-polarized DOS revealed that pure AlNNS is a nonmagnetic semiconductor with a direct bandgap, while transition metals doped AlNNS are DMS or Half Metals (HM). Our results show a high Curie temperature more than 2000 K for Cu, Cr and Mn doping, indicating may be good room-temperature ferromagnetic material for spintronic applications in the future. 4.16% V and Ni atoms and 8.33% of Mn atoms doped AlNNS are HM with 100% spin polarization and appear to be good candidates for spintronic applications and especially as spin filter devices. • AlN Nanosheet doped with 4.16% and 8.33% transition metal atoms. • The doped AlN Nanosheet is diluted magnetic semiconductor or half metal. • Cu, Cr and Mn doped AlN Nanosheet are good for spintronic applications because of high Curie temperature. • V, Ni and Mn doped AlN Nanosheet exhibite half metallic property. [ABSTRACT FROM AUTHOR]

Heusler alloys exhibit diverse functional properties originating from magneto-elastic coupling and attracted significant interest in spintronic applications. We use the full-potential linearized augmented plane wave method to study the electromagnetic, structural, optical and thermoelectric properties of full Heusler Co 2 VGe alloy. The spin-polarized calculations and the spin-orbit coupling effect (SOC) are carried out to study the properties. The optimization is done in both ferromagnetic and non-magnetic states. The electronic structure shows the full-polarization at the Fermi level and confirms the half-metallic nature of Co 2 VGe. A band-gap of 0.89eV is achieved in spin-dn states with mBJ and it decreases with SOC up to 0.82eV. The Cobalt-atoms show major contribution to the overall magnetic behavior of the alloy. The optical and the thermoelectric response of Co 2 VGe are also calculated. In spin-dn states, a high value of Figure of merit i.e. 0.86 is obtained with mBJ and 0.77 with SOC effect at 800 K. • Investigation of the spin-polarized structural, electronic, magnetic and optical properties of full-Heusler Co 2 VGe alloys is done by first principles calculations with spin-orbit coupling effect. • The electronic band structure and density of states (DOS) shows the half-metallic nature of the alloys with mBJ potantial. • The optical parameters such as real and imaginary parts of dielectric function, refractive index, extension coefficients, and energy loss are also calculated. • The high value of ZT in the spin-dn states shows the possibility to use Co 2 VGe in thermoelectric devices. [ABSTRACT FROM AUTHOR]

Graphene has a long spin relaxation length due to its weak intrinsic spin-orbit effect and potentially is attractive for spintronics. Here, the effect of the different applied gate and bias voltages on the time-dependent spin and charge tunneling currents in a system including a magnetic molecule located on a graphene layer with ferromagnetic leads is investigated. We show that the system under investigation could be regulated by applying gate voltage and a time-dependent bias voltage. We also show that the interaction between graphene and magnetic molecule has the principal effect on the electron and spin transport in the system. • Time-dependent spin tunneling current. • Time-dependent charge tunneling current. • Interaction between graphene and magnetic molecule. [ABSTRACT FROM AUTHOR]

We investigated the effect of temperature on the electronic, elastic, and thermodynamic properties of Co -based full-Heusler Co 2 MnSi and Co 2 MnGe. The results show that the alloys are half-metallic ferromagnetic. The spin polarization is 97.90% for Co 2 MnSi , while for Co 2 MnGe is more than 85.3% below 1000 K. The study of elastic constants and their associated parameters predicted that the two alloys are mechanically stable in the temperature range of 0 – 1000 K. Both alloys are ductile, anisotropic, and characterized by ionic bonds. In addition, Co 2 MnGe is less hard than Co 2 MnSi , but the latter is more sensitive to temperature variations than Co 2 MnGe. The electronic and vibrational contributions to the thermodynamic properties were computed separately in the temperature range of 0 K to 1000 K. The high spin polarization and mechanical stability make these alloys more appropriate for spintronic applications. [ABSTRACT FROM AUTHOR]

In this paper, we employed density functional theory using WIEN2k to study structural, mechanical, electrical, magnetic and thermoelectric properties for quaternary Heusler alloys C o Z r T i X (X = G a , S i , S n). The self-consistent field calculation is done with generalized gradient approximation procedure. The structural stability analysis shows that the C o Z r T i X (X = G a , S i , S n) Heusler alloys are stable in Y-I type structure and having ferromagnetic property. In mechanical stability analysis we identified that all the reported Heusler alloys are ductile in nature. Electronic property calculations of C o Z r T i X (X = G a , S i , S n) reveals that all are half-metal, having metallic nature in spin up channel and semiconducting nature in spin down channel. The calculated values of spin magnetic moments are consistent with Slater-Pauling rule. From the transport properties, we identified that both alloys C o Z r T i G a and C o Z r T i S n are showing better thermoelectric performance in higher temperature, while the alloy C o Z r T i S i having reasonable Z T value at room temperature. Hence the reported Heusler alloys C o Z r T i X (X = G a , S i , S n) can be potential candidates for spintronic and thermoelectric applications. • Investigation of spintronic and thermoelectric properties of Heusler alloys CoZrTiX (X = G a , S i , S n). • Heusler alloys CoZrTiX (X = G a , S i , S n) showing half metallic nature with indirect band gap. • All the reported Heusler alloys CoZrTiX (X = G a , S i , S n) showing integer magnetic moments. • The figure of merit values Z T = 2.10, 0.18 and 1.85 for CoZrTiX (X = G a , S i , S n) respectively. • Potential alloys for both spintronic and thermoelectric applications. [ABSTRACT FROM AUTHOR]

The structural, electronic, magnetic, optical, and thermoelectric (TE) features of X 2 CdS 4 (X ​= ​Dy, Tm) spinels are investigated by using the full potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT). The stability of both materials is verified by the negative values of formation enthalpy (ΔH f) and tolerance factor. Both spinels are semiconductors with band gap (E g) of 0.9/1.2 eV in spin up/down channels of Dy 2 CdS 4 , while Tm 2 CdS 4 exhibits E g of 1.04/0.80 eV in spin up/down channel. The calculated magnetic moments (μ B) of spinels Dy 2 CdS 4 and Tm 2 CdS 4 are 19.000 and 8.00 ​μB, correspondingly. Optical features including absorption coefficient α(ω), refractive index n(ω), dielectric constants ε(ω), optical conductivity σ(ω), reflectivity R(ω), and extinction coefficient k(ω) are investigated. Both spinels X 2 CdS 4 (X ​= ​Dy, Tm) discover the maximum photon absorption in the ultraviolet area, which proves that both are acceptable for usage in sensors, optical filters, and optoelectronic applications. BoltzTrap code is utilized to discover TE features like electrical conductivity (σ/τ), Seebeck coefficient (S), thermal conductivity (k/τ), power factor (PF) and figure of merit (ZT). Outcomes of this work enlighten the promising applications of studied spinel compounds in spintronic, optical and TE devices. The stability of both materials is verified by the negative values of formation enthalpy (ΔH f) and tolerance factor. Both Dy 2 CdS 4 and Tm 2 CdS 4 are semiconductors with a direct bandgap (E g) of 0.9 in spin (↑) up and 1.2 ​eV in spin (↓) down for Dy 2 CdS 4 while 1.04 in spin (↑) and 0.80 ​eV in spin (↓) for Tm 2 CdS 4. The calculated magnetic moments (μ B) of spinels Dy 2 CdS 4 and Tm 2 CdS 4 are 19.000 and 8.00 ​μB, correspondingly. Outcomes of this work enlighten the promising applications of studied spinel compounds in spintronic, optical and TE devices. [Display omitted] • The stability of X 2 CdS 4 (X ​= ​Dy, Tm) materials is verified by ΔH f. • Both Dy 2 CdS 4 and Tm 2 Cd S 4 are semiconductors with a direct bandgap (E g). • The calculated magnetic moments of spinels Dy 2 CdS 4 and Tm 2 CdS 4 are 19.000 and 8.00 ​μB, respectively. • Optical features reveal the maximum photon absorption in the ultraviolet region. • Outcomes enlighten the applications of studied spinels in spintronic, optical and TE gadgets. [ABSTRACT FROM AUTHOR]

Despite its important role in understanding ultrafast spin dynamics and revealing novel spin/orbit effects, the mechanism of the terahertz (THz) emission from a single ferromagnetic nanofilm upon a femtosecond laser pump still remains elusive. Recent experiments have shown exotic symmetry, which is not expected from the routinely adopted mechanism of ultrafast demagnetization. Here, by developing a bidirectional pump-THz emission spectroscopy and associated symmetry analysis method, we set a benchmark for the experimental distinction of the THz emission induced by various mechanisms. Our results unambiguously unveil a new mechanism─anomalous Nernst effect (ANE) induced THz emission due to the ultrafast temperature gradient created by a femtosecond laser. Quantitative analysis shows that the THz emission exhibits interesting thickness dependence where different mechanisms dominate at different thickness ranges. Our work not only clarifies the origin of the ferromagnetic-based THz emission but also offers a fertile platform for investigating the ultrafast optomagnetism and THz spintronics.

In this study, density functional theory (DFT) showed that the electronic band profiles of CaCu 3 B 2 Re 2 O 12 (B = Mn, Fe, Co, and Ni) indicate their half-metallic character. The optimized magnetic energy curves in different magnetic phases demonstrated the type-I ferrimagnetic order of all the compounds investigated in this study. The magnetic exchange coupling constants were calculated between the Cu–B, B–Re, and Cu–Re site spins using the Heisenberg model. These interactions generate strong long range Cu(↑)B(↑)Re(↓) order through a super-exchange mechanism. In these perovskites, the anti-parallel moments of Re with B and Cu reduce the net magnetic moments and they are responsible for the ferrimagnetism. The Cu and B 3d-electrons are localized and responsible for the magnetism, and the Re 5d-electrons are delocalized and responsible for the metallic nature. Magnetic susceptibility analysis verified the results estimated using DFT and the Heisenberg model. Due to the 100% spin polarization around the Fermi level, high Curie temperature TC and ferrimagnetism are expected, thereby making these materials suitable for spintronic applications. • The half-metallic character of the CaCu 3 B 2 Re 2 O 12 (B = Mn, Fe, Co and Ni) was revealed by DFT. • Heisenberg model was used for the calculating of the magnetic exchange coupling constants. • It has been shown the perspectives of the CaCu 3 B 2 Re 2 O 12 (B = Mn, Fe, Co and Ni) in spintronic applications. [ABSTRACT FROM AUTHOR]

First principles modeling is conducted to scrutinize the structural, chemical, electronic structures, bonding character, and magneto-optical features of intrinsic or pure anatase TiO 2 , Fe or Mn single-atom doped, and Mn–Fe diatom co-doped anatase TiO 2 systems, respectively. Herein, the spin-polarized density functional theory (DFT) concerted with the on-site Hubbard (U) correction scheme for the Coulomb interaction, is utilized for the exchange-correlation term, as the generalized gradient approximation (GGA)+U. The spin-polarized density of states of Mn mono-atom doped anatase TiO 2 material indicated a magnetic semiconductor attribute for both down/up spin components. Conversely, the outcome spin-polarized density of states of both Fe-doped and Mn–Fe co-doped anatase TiO 2 materials illustrated the emergence of an intermediate band behavior. Accordingly, three magnetic impurity bands are produced in Mn–Fe co-doped anatase TiO 2 , the first two spin-up bands are located just uppermost the valence states nearby the Fermi level and the third spin-up/down band is lying far from the Fermi level just below the minimum conduction band. Interestingly, the spin-polarized charge density displayed an orbital ordering between the O 2p-orbitals and 3d-orbitals of Mn–Fe doped diatoms in the host TiO 2 anatase system. The valuable optical ingredients, such as the optical absorption coefficient, refractive index, reflectivity spectra, optical conductivity, and electron energy loss function, are inspected and discussed. Moreover, the optical absorption coefficient characteristics of the mono-doped Mn/Fe and Mn–Fe co-doped TiO 2 anatase structure displayed a relocation in the absorption feature edges towards the visible electromagnetic radiation regime. This means that the induced impurity bands delineate the essential contributor for boosting the catalytic activity in the visible light. It is expected that the Fe–Mn co-doped anatase TiO 2 system could be a compelling candidate for its ultimate use in the photo-catalysts or magnetic storage devices. • Spin-polarized DOS of Mn mono-atom doped anatase TiO 2 revealed a magnetic semiconductor. • Spin-resolved DOS of Fe doped and Mn–Fe codoped TiO 2 materials, indicated half-metallic state. • Optical spectra showed red-shift for Fe doped and Mn–Fe codoped TiO 2 materials. • Bonding character revealed an orbital ordering for Mn–Fe codoped TiO 2 material. • Both Fe and Mn codoped anatase TiO 2 could be more feasible to enhance catalytic absorption of visible light. [ABSTRACT FROM AUTHOR]

This paper proposes a bio-inspired, low-cost, and highly reliable non-volatile memory design with multi-bit storage capability in one cell to answer the existing memory challenges such as high area and high power consumption. The proposed Multi-level memory (MLM) is based on magnetic tunnel junction (MTJ) as a non-volatile memory element and carbon nanotube field-effect transistors (CNTFET). MLM design provides higher data density, lower area, and lower power consumption per bit of the stored data than single-level memories (SLM). MTJs introduce nonvolatility and near-zero leakage current to the proposed MLM design, which is very important in memory cells. Moreover, as no sequential part is used in the proposed MLM, the proposed memory is also immune to energetic particle strikes. The simulation results indicate that our proposed MLM occupies at least an 80% lower area and offers a 20% lower Power Delay Product (PDP) and an 84% lower Power Delay Area Product (PDAP) than the state-of-the-art designs. Moreover, our results validate the SEU and SEMU immunity of the proposed circuit. Furthermore, the comprehensive Monte-Carlo and corner simulations ascertain the robustness of the proposed MLM memory, even in the presence of a significant process variation. [ABSTRACT FROM AUTHOR]

An ab-initio study on the spin-polarized transport properties of H-passivated Fe-doped graphyne nanoribbons is presented. All the calculations were based on density functional theory (DFT). Doping single magnetic atom on graphyne nanoribbons leads to metallicity which can significantly improve the conductivity. The currents are not degenerate for both up and down spin electrons and they are considerably spin-polarized. Therefore a relatively good spin-filtering can be expected. For configurations with geometric symmetry spin-rectifying is also observed. Therefore they can be applied as a dual spin-filter or a dual spin-diode in spintronic equipment. [ABSTRACT FROM AUTHOR]

Spin-polarized electron transport through a zigzag zinc oxide nanoribbon (ZnONR) has been studied using first-principles transport simulations. Ribbons without edges passivated show 100% spin polarization at small bias voltage independently of width. The ribbons with edge zinc atoms passivated maintain absolute spin-filtering effect in much larger bias region. The results demonstrate that zigzag ZnONRs act as perfect spin-filters in the absence of magnetic electrodes and external fields. [ABSTRACT FROM AUTHOR]

Using spin-polarized density functional theory calculations, we demonstrated that carbon doped boron nitride nanowire (C-doped BNNW) has diverse electronic and magnetic properties depending on position of carbon atoms and their percentages. Our results show that only when one carbon atom is situated on the edge of the nanowire, C-doped BNNW is transformed into half-metal. The calculated electronic structure of the C-doped BNNW suggests that doping carbon can induce localized edge states around the Fermi level, and the interaction among localized edge states leads to semiconductor to half-metal transition. Overall, the bond reconstruction causes of appearance of different electronic behavior such as semiconducting, half-metallicity, nonmagnetic metallic, and ferromagnetic metallic characters. The formation energy of the system shows that when a C atom is doped on surface boron site, system is more stable than the other positions of carbon impurity. Our calculations show that C-doped BNNW may offer unique opportunities for developing nanoscale spintronic materials. [ABSTRACT FROM AUTHOR]

Using the first principles with local density approximation (LDA) and self-interaction-corrected local density approximation (SIC-LDA), the electronic structure of transition metal-doped copper indium sulfide chalcopyrite (CuInS) has been calculated and the effect of low-impurity concentration on magnetic structure has been carried out for both LDA and SIC-LDA; also, the magnetic transition temperature for Cr-doped CuInS was reported in the concentration range of 1-6 % with LDA and SIC-LDA. It is shown that the chalcopyrite semiconductor-doped transition metals (with low concentration) exhibit a high magnetic critical temperature and half-metallic behavior that could have a significant participation in spintronic applications. [ABSTRACT FROM AUTHOR]

Density functional theory based on the full-potential linearized augmented plane wave (FP-LAPW) method is used to investigate the structural, magnetic, electronic, and elastic properties of Heusler alloys CoYIn (Y = Ti, V). It is shown that the calculated spin magnetic moments using the local spin-density approximation (LSDA), generalized gradient approximation (GGA), LSDA + U, and Tran-Blaha (TB)-modified Becke-Johnson (mBJ)-local density approximations (LDA) are in good agreement with the Slater-Pauling rule. The obtained results with LSDA, GGA-PBE, and LSDA + U of the density of states illustrate that both compounds have a metal behavior; however, mBJ-LDA predicts CoVIn alloy to be a half metal. The band structure obtained with mBJ-LDA has an indirect band gap along the Γ- X symmetry with energy of 0.4 eV for CoVIn, and E lies in the middle of the gap; the electrons at the Fermi level are fully spin-polarized. The calculation of elastic properties indicates the stability of these compounds, and they have a ductile behavior. The 3D dependences of Young's modulus exhibit a strong anisotropic character. The high values of the elastic constant C reflect the strength of the bonding Ti (V)-In. [ABSTRACT FROM AUTHOR]

In the last few years there has been a growing interest in the double perovskite (DP) Sr 2 CrReO 6 , as a magnetic material used in spintronics, due to its high Curie temperature ( T C =610 K). Antisite disorder is a defect that affects the spin polarization and the Curie temperature of all PDs. We conducted this work by Monte Carlo simulation to study the effect of the antisite disorder on this compound for two cases: Cr-excess expressed by Sr 2 Cr 1+x Re 1−x O 6 and Re-excess expressed by Sr 2 Cr 1−x Re 1+x O 6 . This simulation has transformed the concept of the antisite conceived as defect, into a tool to explain the role of transition metals, namely Cr and Re, in the stability and the magnetic performance of the compound Sr 2 CrReO 6 . This simulation allows positioning the Cr as a key element in determining the high Curie temperature and the ferromagnetic stability. The effect of crystal field of Re in the disordered sublattice regarding the disorder rates was also explored. [ABSTRACT FROM AUTHOR]

Quantum information and computing are at the forefront of computer science, but their implementation relies on significant developments in materials science. In particular, suitable, lattice-matched substrates for two promising approaches—electrostatically defined quantum dots in Si/SiGe heterostructures, and superconducting circuits containing Josephson junctions—do not exist. Instead, these approaches rely on metamorphic substrates. In this article, we focus on the general structure and requirements of SiGe quantum dot heterostructures, the demands they impose on the underlying substrate, and the impact that properties of the metamorphic substrate have on device performance. Superconductor Josephson junction materials are briefly discussed in a similar fashion, and opportunities for future developments in both systems are described. [ABSTRACT FROM AUTHOR]

This study proposes a spintronic based compact tunable nano‐sized RF oscillator. The proposed design provides parametric performance improvement as compared with the designs already reported in literature. This design also offers higher operating frequency up to range of several GHz, which can be tuned by a DC bias current. The proposed magnetic tunnel junction‐spin torque oscillators (MTJ‐STO) model overcomes the limitation of low output power which is prime issue in spin torque oscillators (STOs). This is achieved by employing multi‐stage amplifier with impedance matching stages. In addition to that, mutual phase locking mechanism of STOs is introduced to act as a remedy for broadening of the spectrum linewidth, which is a critical issue in traditional oscillators. The hybrid model presented in this study contains spin torque based MTJ, which is compatible with CMOS technology. The modelling of proposed circuit has been done in Verilog‐A and simulation results have been verified using HSPICE. [ABSTRACT FROM AUTHOR]

Molecular based spintronic devices offer great potential for future energy-efficient information technology as they combine ultimately small size, high-speed operation, and low-power consumption. Recent developments in combining atom-by-atom assembly with spin-sensitive imaging and characterization at the atomic level have led to a first prototype of an all-spin atomic-scale logic device, but the very low working temperature limits its application. Here, we show that a more stable spintronic device could be achieved using tailored Co-Salophene based molecular building blocks, combined with in situ electrospray deposition under ultrahigh vacuum conditions as well as control of the surface-confined molecular assembly at the nanometer scale. In particular, we describe the tools to build a molecular, strongly bonded device structure from paramagnetic molecular building blocks including spin-wires, gates, and tails. Such molecular device concepts offer the advantage of inherent parallel fabrication based on molecular self-assembly as well as an order of magnitude higher operation temperatures due to enhanced energy scales of covalent through-bond linkage of basic molecular units compared to substrate-mediated coupling schemes employing indirect exchange coupling between individual adsorbed magnetic atoms on surfaces. [ABSTRACT FROM AUTHOR]

Using the full-potential linearized augmented plane-wave (FP-LAPW) calculations with generalized gradient approximation functional (GGA), we investigated the structural, electronic and magnetic properties of the family compounds AlP as ternary diluted semiconductors (DMS)s Al 1− x (TM=Cr,V) x P with concentration of 0.25 and 0.125 in zinc blende phase (B3). The interaction of 3d orbital of transition metal with the 3p states of the four phosphorus atoms who occupy the summits of the tetrahedron resulting from SP3 hybridization, stabilize more the phenomena of magnetization by the effect of Zener's p–d exchange. The analyses of electronic and magnetic properties using the total and partial density of state and bands structure show that Al 1− x Cr x P and Al 1− x V x P are spin-polarized with a half-metallic band gap. We seem that these materials will be among the good candidates for spintronic applications. [ABSTRACT FROM AUTHOR]