SPIN

The rare earth element ytterbium based lead-free perovskite BiYbO₃ was successfully synthesized by cost effective solid-state reaction technique. The analysis of the XRD reflection peaks revealed that BiYbO₃ crystallizes with cubic $Fm3m$ single phase crystal system having cell parameter $a=5.377$Å. The decrease in the dielectric permittivity with frequency was found to follow the accepted Maxwell–Wagner model of interfacial polarization. The reported perovskite was found to be stable up to $450^{°}$C as evident from the low $\text{tan}\delta$ values. The bulk capacitance of BiYbO₃ decreases from 1.619nF/cm² to 0.173nF/cm² with the rise in temperature from $25^{°}$C to $450^{°}$C. The dielectric data shows that BiYbO₃ perovskite follows a negative temperature coefficient of resistance (NTCR) trend. The information obtained from the Nyquist plot and the Cole–Cole electric modulus plot is complementary to each other. The effect of bulk and grain boundary is clearly visible in the Cole–Cole electric modulus plot, whereas a good fit of the equivalent circuit $\{(CQR)(CR)\}$ in the Nyquist plot gave important bulk and grain boundary (capacitance and resistance) parameters. The AC-conductive study for this rare earth perovskite is used to obtain the activation energies to understand the semiconducting behavior of BiYbO₃.

In this paper, we have performed a first-principles study to investigate the electronic structure, magnetic, mechanic and anisotropic elastic properties of Cu₂CrZ (Z=Si and Ge) Full Heusler alloys. The study of these characteristics shows thermodynamic and mechanical stability with cubic symmetry in our compounds and they also have an anisotropic character. The ground-state parameters, i.e., lattice constant, the bulk modulus and the electronic structure are calculated using the full-potential linearized augmented plane wave (FP-LAPW) approach to the density functional theory (DFT) within the generalized gradient approximation (GGA+WC) for the exchange and correlation potential. The objective is to seek stable metallic ferromagnet materials.

Structural, electronic, magnetic and mechanical properties of the Co₂MnGa have been calculated with functional density theory using full potential linear augmented plane wave method as implemented in the Wien2k code. Exchange correlation effects for these properties are treated by generalized gradient approximation while for electronic and magnetic properties, in addition to (WC-GGA) correction, mBJ-GGA scheme was also applied. The stiffness constant of the spin wave and the Curie temperature are calculated. Moreover, mechanical parameters included three elastic constants, compression modulus, Young’s modulus and shear modulus are also investigated. This theoretical study provides detailed information on the compound Co₂MnGa, in different aspects and can also provide information on the application of this material. Obtained data from ab initio calculations are used as input for Monte Carlo simulations to study the magnetic properties and magnetocaloric effect. Transition temperature, magnetic entropy change, adiabatic temperature change and relative cooling power were found.

In this paper, studies of structural as well as electrical characteristics of the double perovskite material FeTiVO₆ (iron titanium vanadate), synthesized by a high-temperature mixed oxide reaction method have been discussed. The room temperature X-ray diffraction analysis confirms the formation of a single-phase orthorhombic structure without any secondary phase. All the electrical characteristics (i.e., dielectric, impedance, conductivity and modulus) of the sample, studied at various temperatures (25–300^°C) and frequencies (1kHz–1MHz), provide many remarkable characteristics of the material. The dielectric parameters as a function of frequency explain the presence of different polarization mechanisms based on the Maxwell–Wagner double-layer model. Impedance analysis describes the grain (bulk) and grain boundary (bulk interior) effect on the material using the equivalent RQC-RC circuits. The presence of non-Debye type of relaxation behavior in the material is confirmed by the depressed semicircles of Nyquist plots. The conductivity study provides information about the CBH and OLPT type of conduction phenomenon. The temperature dependence of leakage current behavior follows the Ohmic (semiconductor) and space charge limited conduction mechanisms at a different range of applied fields. The occurrence of the room temperature hysteresis loop obtained from the PE loop tracer confirms the ferroelectric behavior of the studied compound.

Logic-in memory has emerged as a promising solution to reduce the significant time gap between processor and memory. Simple logics such as NOR and NAND can be embedded in the memory for the purpose of data processing. Besides, ternary logic has been suggested to reduce the interconnects and the complexity of operations. In this paper, a reconfigurable ternary NOR/NAND logic compatible with ternary memories has been proposed. This scheme exploits magnetic tunnel junction as a nonvolatile memory element and a variable resistance, and carbon nanotube field-effect transistor for designing the peripheral circuits to achieve performance and efficiency. The proposed circuit is simulated using HSPICE and the results have validated the correct operation and high performance of the proposed design. Furthermore, the proposed designs are exploited in image processing applications to evaluate their performance in real applications, which gain averagely 52% improvement in the case of data loss.

Magnon scatterings affect the performance of magnonic devices directly, and dynamic dipolar field (DDF) is crucial in the scattering potential. In this paper, a theoretical model of the DDF in low-dimensional magnetic systems is present, and simulations give the summation area to achieve good accuracy in the DDF calculation, though the dipolar field is a long-range interaction. Calculation in a finite-size thin film indicates that due to the breaking of translational symmetry, the DDF increases evidently in the borders and the corners. The DDF near the vertex of the thin film is several orders magnitude higher than that in the inside area, making the corners prominent in the magnon scatterings.

We have investigated the electronic structure of pyrochlore iridate Pr₂Ir₂O₇ compound with Fd-3m space group using first-principle density functional theory calculations. $\mathrm{\text{GGA}}+U+{\mathrm{\text{SO}}}^{111}$ calculations show that the Pr_AFM–Ir_NM state in Pr₂Ir₂O₇ compound is energetically more favorable than the other phases. Combining of the interaction of electronic correlation (U) and spin-orbit coupling (SO) leads to three different phases for this material. (1) An anti-ferromagnetic metal is found by the $\mathrm{\text{GGA}}+U^{\mathrm{\text{Pr}}}$ ($U^{\mathrm{\text{Pr}}}=6$eV) approximation without taking into account the spin orbit interaction. (2) A metal-semimetal transition appears, when the spin-orbit coupling is applied. (3) A semi-conductor characteristic with a narrow gap increases slightly by varying the Hubbard potential of nonmagnetic Ir atoms from 0.5eV to 1.5eV. The effect of the spin orbit (SO) coupling and the interaction (U) clearly influences the Fermi region of the calculated band structures and densities of states of this system. The hydrostatic pressure effect on the energy gap has shown a further advantage in predicting the desired gap value for this kind of materials. The optical properties, including the dielectric function, refractive index, reflectivity and real part of optical conductivity, are calculated for radiation up to 8eV. Overall, however, for both $U^{\mathrm{\text{Ir}}}$ values of Pr₂Ir₂O₇, the compound shows similar optical characteristics.

We report first-principles investigation on structural, electronic and magnetic properties of 3d transition metal element-doped rock-salt calcium selenide Ca${}_{1-x}$TM_xSe (TM = V, Cr and Mn) at concentrations $x$ = 0.0625, 0.125 and 0.25. We performed the calculations in the framework of the density functional theory (DFT) using the full-potential linearized augmented plane waves plus local orbitals (FP-LAPW+lo) method within the Wu–Cohen generalized gradient approximation (WC-GGA) for the structural optimization and the Tran–Blaha modified Becke–Johnson (TBmBJ) potential for the electronic and the magnetic properties. The computed spin-polarized band structures and densities of states show that Ca${}_{1-x}$Cr_xSe compounds at all studied concentrations are half-metallic ferromagnets with a complete spin polarization of 100% at Fermi-level while the Ca${}_{1-x}$V_xSe and Ca${}_{1-x}$Mn_xSe are ferromagnetic semiconductors. The total magnetic moments for Ca${}_{1-x}$V_xSe, Ca${}_{1-x}$Cr_xSe, and Ca${}_{1-x}$Mn_xSe show the integer values of 3${\mu }_B$, 4${\mu }_B$, and 5${\mu }_B$, respectively, with a major contribution of transition metal elements (TM) in the total magnetization. Also, we reported the calculated exchange constants $N_0\alpha$ and $N_0\beta$ and the band edge spin splitting of the valence ($\mathrm{\Delta }{E}_v$) and conduction ($\mathrm{\Delta }{E}_c$) bands. The ferromagnetism of these compounds is due to the super-exchange and the double-exchange mechanisms in addition to the strong p–d exchange interaction. Therefore, the predicted results indicate that the diluted Ca${}_{1-x}$TM_xSe (TM = V, Cr, Mn) compounds are suitable candidates for a possible application in the field of spintronic technology.

In this work, we introduce a computer model and theoretical approach based on the matching technique to investigate the spin precession and the magnetic properties of an ordered magnetic interface joining two ferromagnetic multilayers of type AB, made of 10 spin slabs, obtained by alternative two spin layers A and B. We simulate, particularly, the coherent magnon transmission through spins’ interface, in multilayered thin films, obtained by shearing a part of the film from the other at an angle of 30^∘. The individual and total transmittance of bulk magnons of the thin film, scattering coherently at the shearing interface zone and the localized magnonic spin states, are calculated and analyzed. The transmission and reflection spin modes are derived as elements of a Landauer–Büttiker type scattering matrix. The results highlight the localized spin states on the interface shear domain and their interactions with incident magnons. The evolutions of the magnonic spectra can be presented for arbitrary directions of the incident magnons on the boundary zone, for all accessible frequencies in the propagating bands as well as for the magnetic exchange coupling between each spin A(B) and its adjacent sites and their spin intensity. The results demonstrate the dependence of the magnonic spectra for the perfect multilayered films and at the inhomogeneous domain of the interface shear. The analysis of the spectra illustrates the fluctuations, related to Fano resonances, due to the coupling between travelling magnons and the localized modes in the shear interface domain. The calculated spectra could yield useful information concerning the magnetic parameters of such interface slabs in multilayered films.

We employed the elegant tool of Bopp’s shift and standard perturbation theory methods to obtain a new relativistic and nonrelativistic approximate bound state solution of deformed Klein–Gordon DKG and deformed Schrödinger DSE equations using the modified equal vector scalar Manning–Rosen plus quadratic Yukawa potential (MVSMQY-Ps) model. Furthermore, we have employed the improved approximation to the centrifugal term for some selected diatomic molecules such as N₂, I₂, HCl, CH and LiH in the symmetries of extended quantum mechanics to obtain the approximate solutions. The relativistic shift energy $\mathrm{\Delta }{E}_{rmqy}^{\mathrm{\text{tot}}}(n,\delta ,\eta ,b,A,V_0^{\prime },\mathrm{\Theta },\sigma ,\chi ,j,l,s,m)$ and the perturbative nonrelativistic corrections $\mathrm{\Delta }{E}_{mqy}^{nr}(n,\delta ,\eta ,b,A,V_0^{\prime },\mathrm{\Theta },\sigma ,\chi ,j,l,s,m)$ appeared as a function of the parameters ($\delta ,\eta ,b,A,V_0^{\prime }$), the parameters of noncommutativity ($\mathrm{\Theta },\sigma ,\chi$), in addition to the atomic quantum numbers ($n,j,l,s,m)$. In both relativistic and nonrelativistic problems, we show that the corrections on the spectrum energy are smaller than the main energy in the ordinary cases of RQM and NRQM. A straightforward limit of our results to ordinary quantum mechanics shows that the present result under MVSMQAY-Ps is consistent with what is obtained in the literature. In the new symmetries of NCQM, it is not possible to get the exact analytical solutions for $l=0$ and $l\ne 0$, and can only be solved approximately. We have observed that the DKGE under the MVSMQY-Ps model has a physical behavior similar to the Duffin–Kemmer equation for meson with spin-1; it can describe a dynamic state of a particle with spin-1 in the symmetries of RNCQM. Moreover, we have treated composite systems such as molecules made of $N=2$ particles of masses $m_n(n=1,2)$ in the frame of noncommutative algebra. The NRNCQM and RNCQM results obtained within Bopp’s shift and standard perturbation theory methods overlap entirely with the results obtained by ordinary NCQM, and it displays that the theoretical investigation in this study is excellent.