SPIN

Spin orbit torque magnetic tunnel junction (SOT-MTJ) has been widely used for designing nonvolatile flip-flop (NVFF), thanks to its ultrafast switching speed, zero static power consumption, nearly unlimited endurance, etc. However, in the space environment, the write pulse width of the SOT-MTJ is comparable to radiation-induced current duration. Thus, the SOT-MTJ-based NVFF may suffer from soft error induced by the nonvolatile single event upset (NVSEU) in the backup mode. In this paper, we analyze the sensitive nodes in different work modes and propose the radiation hardening circuits for master–slave NVFF (MS-NVFF) to solve the NVSEUs. Based on a physics-based SOT-MTJ compact model and a 40nm CMOS design kit, the reliability of MS-NVFF is verified by simulation with 2pC charge, which could be reliably integrated into aerospace and avionics electronics in hostile environments.

The magnetocaloric effect, electronic structure and magnetic properties of High Entropy Alloys AlCo_xCr${}_{1-x}$FeNi ($0\le x\le 1$) were calculated using the Monte Carlo simulation, the Korringa–Kohn–Rostoker method combined with the coherent potential approximation (KKR-CPA), method of linear augmented plane wave (FPLAPW) within generalized gradient approximation (GGA) and modified Becke–Johnson potential (TB-mBJ). Density of states of AlCo_xCr${}_{1-x}$FeNi are studied and analyzed. The total magnetic moments of magnetic atoms were calculated and compared with theoretical and experimental results. On the other side, the magnetocaloric effect in AlCo_xCr${}_{1-x}$FeNi was studied by first-principle calculations (FPCs) and Monte Carlo simulations. The magnetic phase transition temperature is estimated. The Curie temperature and exchange integrals were found to decrease with Co substitution. The magnetic entropy changes and relative cooling power are found.

We investigate the role of magnetic impurities in the barrier region in enhancing the torque transferred to the free ferromagnet layer in a non-collinear model tunnel junction. The tunnel junction is modeled using the non-equilibrium Green’s function formalism within the tight-binding approximation. The position of the impurity which is described by the single impurity Anderson model is found to have a profound impact on the trends observed in the spin transfer torque. The parallel ($T_{\parallel }$) torque is observed to have a switch on-off step-like bias behavior while the perpendicular ($T_{\perp }$) torque exhibits a change in sign between the switch-on bias voltages. The spin transfer torque is found to be dramatically enhanced when the impurity is positioned at the interface of a five-layer barrier which is three orders of magnitude larger even at temperatures as high as 200K. With this formulation the effect of Coulomb repulsion at the impurity site on the torque could be deduced and the obtained results are explained in terms of the region-wise electronic density of states in the junction.

We study the thermodynamical properties of two-dimensional mixed spin Ising system consisting of spin-$1∕2$ and spin-1 with four-spin interactions in crystal field interactions on a square lattice within the framework of the finite cluster approximation based on single-site cluster theory. In this paper, the phase diagrams show qualitatively and quantitatively interesting features. In fact, the system exhibits a variety of interesting features resulting from the introduction of the four-spin interactions and the crystal field interactions. Finally, using the same method, we study the behavior of the total magnetization of the Ising model with four-spin interactions in the crystal field to show the existence of compensation points and point intervals for certain values of $D$.

In this study, the ground-state phase diagrams and magnetic properties of mixed spin ($S$-1, $\sigma$-7/2) of the monolayer coronene-like nanostructure have been investigated using Monte Carlo simulations (MCS) in the frame of the Blume Capel model. In the first part, ground-state phase diagrams have been analyzed in order to show the more stable configurations of spins corresponding to various planes. In addition, MCS is applied to study the behavior of the compensation and blocking temperatures by varying the exchange coupling interaction values. Finally, the hysteresis cycle behaviors have been investigated for selected values of exchange coupling parameters, temperature and crystal field. The theoretical results obtained in this study can enrich the magnetic properties of nanosystems and pave the way for researchers to experimentally study monolayer coronene-like nanostructure for future applications in nanotechnology.

Amorphous Fe_xNi${}_{80-x}$B${}_{12}$Si₈ alloys ($x=0.10$ to 16) were fabricated by employing wheel melt spinning process. Measurements of magnetization were made over temperature range of 4.20–360K and with an applied magnetic field up to 160kOe. By making a substitution Ni by Fe, the $T_C$ (Curie temperature) was actually discovered to rise. The spin wave (SW) theory was used to examine the magnetism at low temperatures. At low temperatures (4.20K), magnetization curves were found to obey Bloch’s $T^{3∕2}$ law. Certain important parameters were determined, such as the constant D (SW stiffness) and the distance between interatomic transition metals $(r_{\mathrm{\text{TM}}-\mathrm{\text{TM}}})$ for the different compositions. We employed the law of approach to magnetic saturation to obtain some important parameters, including a random magnetic anisotropy constant $(K_L)$ and then the anisotropy local correlation length. So, it’s worth noting that as Fe concentration rises, the exchange constants, random magnetic anisotropy constant $(K_L)$, and also the ferromagnetic correlation $(R_f)$ rise.

The magnetic tunnel junction is the heart of the STT-MRAM memory. The MTJ is a spintronic device, which is used to store and read the data. With the advancement, most of the work is done online and a useful device is needed in order to store the data. Hence, it is important to design a promising device to store the data for a long time without any damage or loss of information. In this paper, first, we use the MTJ LAB simulator to check the important parameters such as TMR, resistance, and STT components and check how these parameters change for different oxide thicknesses. After this, the device was hybrid with the CMOS for 1-bit STT-MRAM and the results were drawn. So, in this paper, the main focus is to select appropriate oxide thickness and $t_{\mathrm{\text{ox}}}=0.85$nm is used to get better TMR ratio, resistance, and STT-components.

In this paper, the synthesis (solid-state reaction) and characterization (structural, dielectric, electrical, and optical) of the (BiFeO₃)${}_{0.5}$–(CaTiO₃)${}_{0.5}$ (BFCTO) are reported. The structural analysis suggests a distorted rhombohedral crystal symmetry (#R-3m) with average crystallite of 93.2nm and lattice strain of 0.105%. The scanning electron microscopy (SEM) and energy dispersive microstructural analysis X-ray (EDAX) analyses suggest that the grains are uniformly distributed with well-defined grain boundaries and the presence of all constituent elements, respectively. The average grain size is about $(4.1\pm 0.3)\mu$m as calculated from the ImageJ software. Both the temperature and the frequency-dependent dielectric study predict high dielectric constant of 9000 at 1kHz, low dielectric loss, the phase transition from ferroelectric to paraelectric at 410^∘C, and negative temperature coefficient of resistance (NTCR) character. The impedance spectroscopy provides the effect of grains and grain boundaries on the conductivity mechanism and exhibits the non-Debye type of relaxation. The decreasing radius of semicircular arcs with temperature in both Nyquist and Cole–Cole plots supports the NTCR and thermally activated conduction mechanism. The polarization–electric field (P–E) loop study confirms the ferroelectric character of the sample. The study of the $I$–$V$ plot suggests the leakage current in the mA range and ohmic conducting nature. The Fourier transform infrared spectroscopy (FTIR) spectrum suggests the presence of all constituent elements, whereas the bandgap energy from UV–Visible study is about 1.43eV, which is useful in photovoltaic applications.