SPIN

This study delves into the magnetic behavior of sulflower-like nanostructures, particularly focusing on compensation and blocking temperatures. Through the construction of a phase diagram detailing crystal and external magnetic fields (D/$J_{\sigma \sigma }$, H/$J_{\sigma \sigma })$, stable phases were identified, shedding light on how spin configurations evolve with variations in H/$J_{\sigma \sigma }$ and D/$J_{\sigma \sigma }$. The analysis of blocking temperature ($T_B$/$J_{\sigma \sigma })$ and compensation temperature ($T_{\mathrm{\text{comp}}}$/$J_{\sigma \sigma })$ relative to $J_{\sigma s}$/$J_{\sigma \sigma }$, $J_{ss}$/$J_{\sigma \sigma }$ and H/$J_{\sigma \sigma }$ reveals intriguing patterns. Additionally, an examination of hysteresis cycles uncovers dynamic behavior, characterized by multiple loops and magnetization plateaus. These findings open promising avenues for spintronic applications of sulflower-like nanostructures, offering valuable insights into their magnetic behavior and potential utility in future technologies. This involves the fabrication of high-density data storage devices, where its tunable magnetic characteristics may result in the development of effective data manipulation and storage components.

Arrays of interconnected magnetic nanorings show emergent dynamics arising from stochastic interactions at junctions between rings. These global emergent properties have already shown potential as a platform for reservoir computing. However, their experimental computational performance has been limited by the use of a single-dimensional global measurement, their magnetoresistance, as an output, masking much of the underlying state information. Here, we show in both simulation and experiment the potential of using the spin wave spectra of such arrays of nanorings to produce a fingerprint of the number and orientation of the internal magnetic states, providing a route towards a multi-dimensional output with which to perform computation. We show that the spectra fulfill the two criteria for reservoir computing: a nonlinear response to an input stimulus, and a fading memory.

Ultra-broadband and large angle metamaterial absorber (MMA) based on three dimensional anisotropic resistive film structure and magnetic material was proposed. The designed MMA consists of four layers, the top layer is resistive film structure, the second layer is tri-dimensional cross-resistive film metamaterial structure, the third layer is conditional magnetic material, and the bottom is metal ground plane. Owing to the three-dimensional anisotropic metamaterial structure, the designed absorber can realize ultra-broadband and large angle absorption. Simulation result shows that the absorption rate is more than 90% in the frequency range of 1.3–30GHz with TM polarized wave with incident angle 82^∘, and simultaneous realizing the large angle absorption about 70% as the incident angle changes from 60^∘ to 87^∘. In order to analyze the mechanism of the ultra-broadband and larger angle absorption, we also simulated the results without the top layer or the magnetic material absorbers to search the cause of ultra-broadband and larger angle absorption. In succession, surface current distributions and power loss density on different structural layers of absorber at different frequencies are analyzed. The absorption spectrums under different polarization angles also have the same absorption effect due to the four-fold rotationally symmetric unit structure. We believe that the absorber will may have many potential applications in some field.

The effect of in-plane wave vectors on spin-dependent transport properties is examined theoretically. In this work, ZnO/Zn${}_{1-x}$Cd_xO double barrier-heterostructure with an identical barrier width of 30 Å is considered. The transmission coefficient is calculated by using the transfer matrix. The role of Dresselhaus spin–orbit coupling is accounted. The in-plane wave vector influences the energy separation between different orientations of the electrons. The spin separation ranges from 0.002meV to 0.008meV as the in-plane wave vector changes from $1\times 10^8$/m to $5\times 10^8$/m. The degree of spin polarization is enhanced at the high magnitude of the in-plane wave vector. The dwell time of the incident electrons is examined. The role of heterostructure strain on spin-transport properties is also reported. About 73% of polarization efficiency is observed in this study when the heterostructure strain is observed.

Complementary metal oxide semiconductor (CMOS) is an extensively used promising technology for developing integrated circuits, such as memory chips, microprocessors and microcontrollers with high noise immunity. However, deep scaling of CMOS technology ($<90$ nm) suffers from various impediments at the device and architectural level, namely high leakage current, increased radiation sensitivity, more die area and dynamic power dissipation. To overcome these limitations of CMOS devices, logic-in-memory (LIM) structures have been developed with spin-based devices like Magnetic Tunnel Junctions (MTJs). MTJs are not affected by external particles and feature zero standby power. The MTJs in magnetic logic circuit and magnetic random-access memory (MRAM) applications are robust against radiation, high speed, low leakage power, nonvolatility and easily compatible with the back end. Existing magnetic full adder (MFA) techniques require augmented circuits for seamless operation. A major drawback in the existing MFA structure is the data loss due to single event upset (SEU) and poor sensitivity of pre-charge sense amplifiers (PCSAs) to input arrival timing. This paper proposes an MTJ-based nonvolatile magnetic full adder (NV-MFA) using 10T logic to address the above issues. The output buffer circuit is designed with a read-write parallel switching (RWPS) writing circuit based on spin orbit torque (SOT). The proposed circuit is more immune to the fault occurrence compared with the existing pass transistor and PCSA-based MFA logic. It leads to reduced power dissipation, die area and delay. Perpendicular anisotropy MTJ (CoFeB/MgO/CoFeB) model is chosen for the MTJ structure. It is suitable for efficient MRAM structure. The transient response is verified on Cadence virtuoso using 45nm gpdk CMOS technology. The simulation analysis shows the performance is enhanced with fault-free data output and improved reliability compared with previous MFAs.

In this paper, a quaternary true random number generator (QTRNG) is designed and simulated. The proposed QTRNG capitalizes on the stochastic behavior of the magnetic tunnel junction (MTJ) device at currents below the critical current, alongside the adjustable threshold voltage of the carbon nanotube field-effect transistor (CNTFET). To maintain uniformity in the ratio of numbers generated by the QTRNG and mitigate the impact of fabrication process variations, a mid-level processing block has been incorporated. Simulation results show that the proposed QTRNG occupies at least 7% less area and can produce 36% more digits per second compared to existing binary and ternary true random number generators.

A hybrid magnetic-electric-barrier nanostructure consisting of a $\delta$-magnetic-barrier and a rectangular-electric-barrier can be constructed by patterning a half-infinitely wide ferromagnetic stripe and a Schottky-metal stripe on the surface of GaAs/Al_xGa${}_{1-x}$As. This hybrid nanostructure was recently demonstrated to act as an electron-momentum filter. Here, we introduce a tunable $\delta$-potential by the atomic-layer doping to manipulate this momentum filter. The wave-vector filtering is found to be associated with this $\delta$-doping, since the effective potential experienced by electrons in the device depends on the $\delta$-potential. It also is found that the wave-vector filtering efficiency can be effectively controlled by changing the weight or position of the $\delta$-doping. These interesting findings may be useful for designing structurally manipulable electron-momentum filters for nanoelectronics device applications.

Tunnel magneto-resistance (TMR) ratio is studied in double-barrier magnetic tunnel junctions with a central ferrimagnet layer (DBMTJs-FI). The effects of spin–orbit coupling (SOC) within the FI layer on the TMR ratio are also taken into account. A tight-binding model is applied to compute transmission function by the nonequilibrium Green’s function method. A higher TMR ratio is found for the DBMTJs-FI compared to that for the DBMTJs with a central ferromagnet layer (DBMTJs-F) in the absence of the SOC. Therefore, a novel application for the FIs is presented by these findings in the field of spintronics.

Magnetic properties and hysteresis of a mixed spins (1, 2) hexagonal Ising nanowire with core–shell structure in the presence of lattice anisotropy and external magnetic field are investigated by using Monte Carlo simulation based on the Metropolis algorithm. First, we analyze the ground state phase diagrams to discover all probable and stable configurations based on minimizing the system energy. The effects of the exchange couplings ($J_{\mathrm{\text{int}}}$, $J_s)$ and the single-ion anisotropies ($D_c$, $D_s)$ on the magnetic quantities of the system, namely, the total magnetization, the transition temperatures and the hysteresis curves. Several characteristic behaviors are found, such as the appearance and the compensation behavior, which is of crucial importance for technological applications such as thermo-optical recording. Additionally, under certain physical parameters, multiple cycle hysteresis loops, such as single and triple hysteresis loops, that exhibit different step effects and various forms, are observed.

Current-induced spin–orbit torque (SOT) switching is an efficient manipulation of noncollinear antiferromagnet states with exotic topological transport properties. However, stable switching of the spin chirality is still challenging, and the role of symmetry in SOT-driven switching is unclear. Here, we introduce asymmetric interfacial Dzyaloshinskii–Moriya interaction (DMI) by varying the value of one of the DMI vectors ($D_3)$. By using an atomistic model, it is shown that in Mn₃Ir monolayer, stable spin chiral switching driven by SOT can be realized. In particular, it can effectively reduce the critical switching current density and the switching time by increasing the value of $D_3$. We also provide switching phase diagrams with different $D_3$ and SOT coefficients. Our results help further understand the switching mechanism of antiferromagnets and develop promising applications of antiferromagnetic (AFM) spintronic devices.