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This investigation presents a self-powered, solar-blind photodetector utilizing a low-temperature fabricated crystalline NiO/ZnGa 2 O 4 heterojunction with a staggered type-II band alignment. The device leverages the pyrophototronic effect (PPE), combining the photoelectric effect in the p-n junction and the pyroelectric effect in the non-centrosymmetric ZnGa 2 O 4 crystal. This synergistic effect enhances the photodetector's performance parameters, thereby outperforming traditional solar-blind photodetectors. The device demonstrates an extremely low dark current of 5.39 fA, a high responsivity of 88 mA/W, and a very high specific detectivity of 2.03 × 10 14 Jones under 246 nm light irradiation at 0 V bias. Significantly, due to the PPE, the impact demonstrates a much-enhanced transient response when tested under various light intensities, ranging from 18 to 122 μW/cm 2 . The photodetector shows a high responsivity of 338 A/W and an outstanding detectivity of 7.1 × 10 18 Jones with an applied voltage of -13 V, showing its ability to detect weak signals. Single-crystalline ZnGa 2 O 4 fabricated by MOCVD exhibits significant absorption of deep UV light, and the heterojunction's type-II band alignment with NiO is responsible for its exceptional self-powered pyrophotoelectric detecting and rectifying capabilities.

Solving certain combinatorial optimization problems like Max-Cut becomes challenging once the graph size and edge connectivity increase beyond a threshold, with brute-force algorithms which solve such problems exactly on conventional digital computers having the bottleneck of exponential time complexity. Hence currently, such problems are instead solved approximately using algorithms like Goemans-Williamson (GW) algorithm, run on conventional computers with polynomial time complexity. Phase binarized oscillators (PBOs), also often known as oscillator Ising machines, have been proposed as an alternative to solve such problems. In this paper, restricting ourselves to the combinatorial optimization problem Max-Cut solved on three kinds of graphs (Mobius Ladder, random cubic, Erdös Rényi) up to 100 nodes, we empirically show that computation time/time to solution (TTS) for PBOs (captured through Kuramoto model) grows at a much lower rate (logarithmically:O(log(N)), with respect to graph size N ) compared to GW algorithm, for which TTS increases as square of graph size (O( N 2 )). However, Kuramoto model being a physics-agnostic mathematical model, this time complexity/ TTS trend for PBOs is a general trend and is device-physics agnostic. So for more specific results, we choose spintronic oscillators, known for their high operating frequency (in GHz), and model them through Slavin's model which captures the physics of their coupled magnetization oscillation dynamics. We thereby empirically show that TTS of spintronic oscillators also grows logarithmically with graph size (O(log(N)), while their accuracy is comparable to that of GW. So spintronic oscillators have improved time complexity over GW algorithm. For large graphs, they are expected to compute Max-Cut values much faster than GW algorithm, as well as other oscillators operating at lower frequencies, while maintaining the same level of accuracy., (© 2024 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.)

Fe[Formula: see text]Sn[Formula: see text] is a topological kagome ferromagnet that possesses numerous Weyl points close to the Fermi energy, which can manifest various unique transport phenomena such as chiral anomaly, anomalous Hall effect, and giant magnetoresistance. However, the magnetodynamic properties of Fe[Formula: see text]Sn[Formula: see text] have not yet been explored. Here, we report, for the first time, the measurements of the intrinsic Gilbert damping constant ([Formula: see text]), and the effective spin mixing conductance (g[Formula: see text]) of Pt/Fe[Formula: see text]Sn[Formula: see text] bilayers for Fe[Formula: see text]Sn[Formula: see text] thicknesses down to 2 nm, for which [Formula: see text] is [Formula: see text], and g[Formula: see text] is [Formula: see text]. The films have a high saturation magnetization, [Formula: see text], and large anomalous Hall coefficient, [Formula: see text]. The large values of g[Formula: see text], together with the topological properties of Fe[Formula: see text]Sn[Formula: see text], make Fe[Formula: see text]Sn[Formula: see text]/Pt bilayers useful heterostructures for the study of topological spintronic devices., (© 2024. The Author(s).)

As a topological Dirac semimetal with controllable spin-orbit coupling and conductivity, PtSe 2 , a transition-metal dichalcogenide, is a promising material for several applications, from optoelectrics to sensors. However, its potential for spintronics applications has yet to be explored. In this work, we demonstrate that the PtSe 2 /Ni 80 Fe 20 heterostructure can generate large damping-like current-induced spin-orbit torques (SOT), despite the absence of spin-splitting in bulk PtSe 2 . The efficiency of charge-to-spin conversion is found to be -0.1 ± 0.02 nm -1 in PtSe 2 /Ni 80 Fe 20 , which is 3 times that of the control sample, Ni 80 Fe 20 /Pt. Our band structure calculations show that the SOT due to PtSe 2 arises from an unexpectedly large spin splitting in the interfacial region of PtSe 2 introduced by the proximity magnetic field of the Ni 80 Fe 20 layer. Our results open up the possibilities of using large-area PtSe 2 for energy-efficient nanoscale devices by utilizing proximity-induced SOT.

Structural elements are subjected to different types of loads, one of which is a torsional load. Due to the complexity of the analysis, torsion was not given much importance in earlier days. With stringent updates in codal provisions and due to architectural modifications, torsion is now considered one of the major parameters for structural design. The main aim of this paper is to analyze distressed elements due to torsion. It highlights different approaches, such as destructive and non-destructive processes, to be adopted to estimate the torsional parameters of a ferrocement "U" wrapped beam. The destructive method is the experimental determination of parameters, which is absolutely necessary. The non-destructive method includes an analytical method based on a softened truss model as well as a soft computing method. The soft computing method is based on the regression coefficient analysis method along with two recent optimization algorithms, i.e., (1) ARO (artificial rabbits optimization) and (2) DAOA (dynamic arithmetic optimization algorithm). The predicted results are found to be in agreement with the experimental values (destructive method). Lastly, the obtained results from both proposed methods are analyzed, and it is found that both algorithms can be utilized in any engineering problem to determine the global optimum value with corresponding input optimal settings. As the experimental method is time-consuming and expensive, analytical, and soft computing methods can be preferred over the experimental method.

Here, we report on the comprehensive growth, characterization, and optoelectronic application of large-area, two-dimensional germanium selenide (GeSe) layers prepared using the pulsed laser deposition (PLD) technique. Back-gated phototransistors based on few-layered 2D GeSe have been fabricated on a SiO 2 /Si substrate for ultrafast, low noise, and broadband light detection, showing spectral functionalities over a broad wavelength range of 0.4-1.5 μm. The broadband detection capabilities of the device have been attributed to the self-assembled GeO x /GeSe heterostructure and sub-bandgap absorption in GeSe. Besides a high photoresponsivity of 25 AW -1 , the GeSe phototransistor displayed a high external quantum efficiency of the order of 6.14 × 10 3 %, a maximum specific detectivity of 4.16 × 10 10 Jones, and an ultralow noise equivalent power of 0.09 pW/Hz 1/2 . The detector has an ultrafast response/recovery time of 3.2/14.9 μs and can show photoresponse up to a high cut-off frequency of 150 kHz. These promising device parameters exhibited by PLD-grown GeSe layers-based detectors make it a favorable choice against present-day mainstream van der Waals semiconductors with limited scalability and optoelectronic compatibility in the visible-to-infrared spectral range.

Spin-to-charge conversion is an essential requirement for the implementation of spintronic devices. Recently, monolayers (MLs) of semiconducting transition-metal dichalcogenides (TMDs) have attracted considerable interest for spin-to-charge conversion due to their high spin-orbit coupling and lack of inversion symmetry in their crystal structure. However, reports of direct measurement of spin-to-charge conversion at TMD-based interfaces are very much limited. Here, we report on the room-temperature observation of a large spin-to-charge conversion arising from the interface of Ni 80 Fe 20 (Py) and four distinct large-area (∼5 × 2 mm 2 ) ML TMDs, namely, MoS 2 , MoSe 2 , WS 2 , and WSe 2 . We show that both spin mixing conductance and the Rashba efficiency parameter (λ IREE ) scale with the spin-orbit coupling strength of the ML TMD layers. The λ IREE parameter is found to range between -0.54 and -0.76 nm for the four ML TMDs, demonstrating a large spin-to-charge conversion. Our findings reveal that the TMD/ferromagnet interface can be used for efficient generation and detection of spin current, opening new opportunities for novel spintronic devices.

Spin pumping has been considered a powerful tool to manipulate the spin current in a ferromagnetic/nonmagnetic (FM/NM) system, where the NM part exhibits large spin-orbit coupling (SOC). In this work, the spin pumping in β-W/Interlayer (IL)/Co 2 FeAl (CFA) heterostructures grown on Si(100 ) is systematically investigated with different ILs in which SOC strength ranges from weak to strong. We first measure the spin pumping through the enhancement of effective damping in CFA by varying the thickness of β-W. The damping enhancement in the bilayer of β-W/CFA (without IL) is found to be ∼50% larger than the Gilbert damping in a single CFA layer with a spin diffusion length and spin mixing conductance of 2.12 ± 0.27 nm and 13.17 ± 0.34 nm -2 , respectively. Further, the ILs of different SOC strengths such as Al, Mg, Mo, and Ta were inserted at the β-W/CFA interface to probe their impact on damping in β-W/ILs/CFA. The effective damping reduced to 8% and 20% for Al and Mg, respectively, whereas it increased to 66% and 75% with ILs of Mo and Ta, respectively, compared to the β-W/CFA heterostructure. Thus, in the presence of ILs with weak SOC, the spin pumping at the β-W/CFA interface is suppressed, while for the high SOC ILs effective damping increased significantly from its original value of β-W/CFA bilayer using a thin IL. This is further confirmed by performing inverse spin Hall effect measurements. In summary, the transfer of spin angular momentum can be significantly enhanced by choosing a proper ultrathin interface layer. Our study provides a tool to increase the spin current production by inserting an appropriate thin interlayer which is useful in modifying the heterostructure for efficient performance in spintronics devices.

Fe 3 Sn 2 , a kagome ferromagnet, is a potential quantum material with intriguing topological features. Despite substantial experimental work on the bulk single crystals, the thin film growth of Fe 3 Sn 2 remains relatively unexplored. Here, we investigate the effect of two different seed layers (Ta and Pt) on the growth of Fe 3 Sn 2 thin films. We demonstrate the growth of polycrystalline Fe 3 Sn 2 thin films on Si/SiO 2 substrates by room temperature sputter deposition, followed by in situ annealing at 500 °C. Our structural and magnetic measurements indicate that a pure ferromagnetic phase is formed for the Pt/Fe 3 Sn 2 thin films with higher saturation magnetization of M s = 464 emu cc -1 , while a mixed-phase (consisting of ferromagnetic, Fe 3 Sn 2 and antiferromagnetic, FeSn) is formed for the Ta/Fe 3 Sn 2 thin films with a lower M s of 240 emu cc -1 . The Pt/Fe 3 Sn 2 thin films also exhibit an anomalous Hall coefficient, R s ≈ 2.6 × 10 -10 Ω cm -1 G -1 at room temperature, which is two order of magnitude higher compared to 3d-transition metal ferromagnets. A non-zero temperature-independent anomalous Hall conductivity σ intxy = (23 ± 11) Ω -1 cm -1 indicates an intrinsic mechanism of anomalous Hall effect originating from Berry curvature. These results are important for realizing novel topological spintronic devices on a CMOS-compatible substrate.

We numerically investigate the ultrafast nucleation of antiferromagnetic (AFM) skyrmion using in-plane spin-polarized current and present its key advantages over out-of-plane spin-polarized current. We show that the threshold current density required for the creation of AFM skyrmion is almost an order of magnitude lower for the in-plane spin-polarized current. The nucleation time for the AFM skyrmion is found to be [Formula: see text] ps for the corresponding current density of 1-[Formula: see text]. We also demonstrate ultrafast nucleation of multiple AFM skyrmions that is possible only with in-plane spin polarized current and discuss how the current pulse width can be used to control the number of AFM skyrmions. The results show more than one order of magnitude improvement in energy consumption for ultrafast nucleation of AFM skyrmions using in-plane spin-polarized current, which is promising for applications such as logic gates, racetrack memory, and neuromorphic computing.

In this Letter, the formatting of some of the crystallographic axes was incorrect. This has been corrected online.

Magnetic skyrmions are topological spin-textures having immense potential for energy efficient spintronic devices. Here, we report the observation of stable skyrmions in unpatterned Ta/Co 2 FeAl(CFA)/MgO thin film heterostructures at room temperature in remnant state employing magnetic force microscopy. It is shown that these skyrmions consisting of ultrathin ferromagnetic CFA Heusler alloy result from strong interfacial Dzyaloshinskii-Moriya interaction (i-DMI) as evidenced by Brillouin light scattering measurements, in agreement with the results of micromagnetic simulations. We also emphasize on room temperature observation of multiple skyrmions which can be stabilized for suitable combinations of CFA layer thickness, perpendicular magnetic anisotropy, and i-DMI. These results provide a significant step towards designing of room temperature spintronic devices based on skyrmions in full Heusler alloy based thin films.

The spin Hall effect (SHE) 1-5 achieves coupling between charge currents and collective spin dynamics in magnetically ordered systems and is a key element of modern spintronics 6-9 . However, previous research has focused mainly on non-magnetic materials, so the magnetic contribution to the SHE is not well understood. Here we show that antiferromagnets have richer spin Hall properties than do non-magnetic materials. We find that in the non-collinear antiferromagnet 10 Mn 3 Sn, the SHE has an anomalous sign change when its triangularly ordered moments switch orientation. We observe contributions to the SHE (which we call the magnetic SHE) and the inverse SHE (the magnetic inverse SHE) that are absent in non-magnetic materials and that can be dominant in some magnetic materials, including antiferromagnets. We attribute the dominance of this magnetic mechanism in Mn 3 Sn to the momentum-dependent spin splitting that is produced by non-collinear magnetic order. This discovery expands the horizons of antiferromagnet spintronics and spin-charge coupling mechanisms.

An important property of spin-torque nano-oscillators (STNOs) is their ability to produce a frequency modulated (FM) signal, which is very critical for communication applications. We here demonstrate a novel single sideband (SSB) modulation phenomenon using a magnetic tunnel junction (MTJ)-based STNO, which saves transmission bandwidth and in principle should minimize attenuation for wireless communication. Experimentally, lower single sidebands (LSSBs) have been successfully demonstrated over a wide range of modulation frequency, f m  = 150 MHz-1 GHz. The observed LSSBs are determined by the intrinsic properties of the device, which can be modeled well by a nonlinear frequency and amplitude modulation formulation and reproduced in macrospin simulations. Moreover, our macrospin simulation results show that the range of modulation current and modulation frequency for generating SSBs can be controlled by the field-like torque and biasing conditions.

Dissipative solitons have been reported in a wide range of nonlinear systems, but the observation of their magnetic analog has been experimentally challenging. Using spin transfer torque underneath a nanocontact on a magnetic thin film with perpendicular magnetic anisotropy (PMA), we have observed the generation of dissipative magnetic droplet solitons and report on their rich dynamical properties. Micromagnetic simulations identify a wide range of automodulation frequencies, including droplet oscillatory motion, droplet "spinning," and droplet "breather" states. The droplet can be controlled by using both current and magnetic fields and is expected to have applications in spintronics, magnonics, and PMA-based domain-wall devices.

We report local and non-local measurements in pin-hole dominated mesoscopic multigraphene spin-valves. Local spin-valve measurements show spurious switching behavior in resistance during magnetic field sweeping similar to the signal observed due to spin injection into multigraphene. The switching behavior has been explained in terms of a local Hall effect due to a thickness irregularity of the tunnel barrier. The local Hall effect appears due to a large local magnetostatic field produced near the roughness in the AlO(x) tunnel barrier. In our samples the resistance change due to the local Hall effect remains negligibly small above 75 K. A strong local Hall effect might hinder spin injection into multigraphene, resulting in no spin signal in non-local measurements.

Spin-torque oscillators offer a unique combination of nanosize, ultrafast modulation rates and ultrawide band signal generation from 100 MHz to close to 100 GHz. However, their low output power and large phase noise still limit their applicability to fundamental studies of spin-transfer torque and magnetodynamic phenomena. A possible solution to both problems is the spin-wave-mediated mutual synchronization of multiple spin-torque oscillators through a shared excited ferromagnetic layer. To date, synchronization of high-frequency spin-torque oscillators has only been achieved for two nanocontacts. As fabrication using expensive top-down lithography processes is not readily available to many groups, attempts to synchronize a large number of nanocontacts have been all but abandoned. Here we present an alternative, simple and cost-effective bottom-up method to realize large ensembles of synchronized nanocontact spin-torque oscillators. We demonstrate mutual synchronization of three high-frequency nanocontact spin-torque oscillators and pairwise synchronization in devices with four and five nanocontacts.

We discuss the coherence of magnetic oscillations in a magnetic tunnel junction based spin torque oscillator as a function of the external field angle. Time-frequency analysis shows mode hopping between distinct oscillator modes, which arises from linear and nonlinear couplings in the Landau-Lifshitz-Gilbert equation, analogous to mode hopping observed in semiconductor ring lasers. These couplings and, therefore, mode hopping are minimized near the current threshold for the antiparallel alignment of free-layer with reference layer magnetization. Away from the antiparallel alignment, mode hopping limits oscillator coherence.

Magnetic anisotropy, magnetization reversal and the magnetooptic Kerr effect in Co(x)Mn(y)Ge(z) have been studied over a range of compositions between 0 and 50 at.% of Ge and between 1 and 3 in the Co to Mn atomic ratio, including the Heusler alloy Co(2)MnGe. A strong quadratic magnetooptic Kerr effect has been observed within a narrow region of composition centered around the Co to Mn atomic ratio of 2, which has been used to probe and quantify the magnetic anisotropy and magnetization reversal of the system. The anisotropy is sixfold with a weak uniaxial component, and it exhibits sensitive dependence on composition, especially on the atomic ratio between Co and Mn. The magnetization reversal process is consistent with the single-domain Stoner-Wohlfarth model.