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Understanding the internal magnetization structure of an individual ferromagnetic nanoparticle (MNP) is crucial for deciphering its magnetic characteristics. Unfortunately, while certain techniques can measure the magnetic properties of an individual MNP, they fall short of accurately detecting the internal magnetization structure. In this work, micromagnetic simulations were employed to construct the internal magnetization structure of an individual CoFe2O4 (CFO) nanopyramid, and the energy jump behavior during the magnetization process was successfully explained, with simulation results aligning with dynamic cantilever magnetometry (DCM) experimental outcomes. Subsequently, the external stray field of the nanopyramid was simulated, and the stray field gradient map revealed distinct bright and dark regions corresponding to the reverse and forward saturation magnetizations of the CFO nanopyramid. This result is possible to be verified by magnetic force microscopy (MFM) measurements of individual CFO nanopyramids. The confidence in the accuracy of the simulated internal magnetization structure was significantly enhanced by independently verifying the micromagnetic simulation results through DCM and MFM experiments. Our work proposes a convenient and cost-effective method for studying the internal magnetization structure of individual MNPs. [ABSTRACT FROM AUTHOR]

We investigated the magnetic properties of Sendust (Fe-Al-Si) alloys not only at 0 K but also at finite temperatures by means of the first-principles calculations assuming A2, B2, and D 0 3 structures. We confirmed that the itinerant characteristics of 3 d electrons of Fe are not negligible and a significantly small exchange stiffness constant exists at zero temperature in a B2 structure. However, the calculated Curie temperatures are in the same order for all structures; this indicates that the Curie temperature cannot be determined only by the exchange interactions at zero temperature in itinerant electron systems. Temperature dependence of the exchange interaction, namely, spin configuration dependence, also might be important for determining it. In addition, this property might also be related to the unique behavior of the temperature dependence of the exchange stiffness constant for the B2 structure, which does not decrease monotonically as temperatures increase, contrary to the behavior expected from the Heisenberg model. In addition, we investigated composition dependence on the exchange stiffness constant at zero temperature and confirmed that the substitution of Si with Al could improve the amplitude of the exchange stiffness constant at zero temperature for all structures. [ABSTRACT FROM AUTHOR]

The development and technological applications of molecular spin systems require versatile experimental techniques to characterize and control their static and dynamic magnetic properties. In the latter case, bulk spectroscopic and magnetometric techniques, such as AC magnetometry and pulsed electron paramagnetic resonance, are usually employed, showing high sensitivity, wide dynamic range, and flexibility. They are based on creating a nonequilibrium state either by changing the magnetic field or by applying resonant microwave radiation. Another possible source of perturbation is a laser pulse that rapidly heats the sample. This approach has proven to be one of the most useful techniques for studying the kinetics and mechanism of chemical and biochemical reactions. Inspired by these works, we propose an inductive detection of temperature-induced magnetization dynamics as applied to the study of molecular spin systems and describe the general design and construction of a particular induction probehead, taking into account the constraints imposed by the cryostat and electromagnet. To evaluate the performance, several coordination compounds of VO2+, Co2+, and Dy3+ were investigated using low-energy pulses of a terahertz free electron laser of the Novosibirsk free electron laser facility as a heat source. All measured magnetization dynamics were qualitatively or quantitatively described using a proposed basic theoretical model and compared with the data obtained by alternating current magnetometry. Based on the results of the research, the possible scope of applications of inductive detection and its advantages and disadvantages in comparison with standard methods are discussed. [ABSTRACT FROM AUTHOR]

Programmable and non-volatile spin-based logic devices have attracted significant interest for use in logic circuits. Realization of logic operations via spin–orbit torque (SOT) driven magnetization switching could be a crucial step in the direction of building logic-in-memory architectures. In this work, we demonstrate experimentally, the realization of four logic operations in a heavy metal/ferrimagnet bilayer structure via SOT switching. We also propose a general scheme for choosing input parameters to achieve programmable logic operations. The bulk and tunable perpendicular magnetic anisotropy and relatively lower saturation magnetization in ferrimagnets are found to make them more energy efficient in performing logic operations, as compared to conventional ferromagnets. Thus, ferrimagnets are promising candidates for use in logic-in-memory architectures, leading to the realization of user-friendly spin logic devices in the future. [ABSTRACT FROM AUTHOR]

This paper reports on the application of a near-infrared (NIR) imaging system for visualizing heat transfer dynamics from a bulk gadolinium (Gd) sample to the surrounding water during the magnetization/demagnetization process of the magnetocaloric effect (MCE). The suggested approach relied on the spectral variation in water absorption band at 1150 nm wavelength within the NIR spectrum. An experimental setup integrated a telecentric uniform-illumination system, a halogen lamp, and an NIR camera to enable real-time monitoring of a single magnetization and demagnetization cycle induced by an external magnetic field, which was generated by a permanent-magnet-based magnetic circuit. Two-dimensional absorbance images captured during this cycle clearly depicted the thermal energy generated by the MCE in water. Furthermore, an analysis of the thermal boundary layer and the quantification of heat transfer from Gd to water provided insights into the dynamics over time. These results indicated the potential of our NIR imaging techniques in optimizing thermal–fluid interactions within MCE systems, thereby improving the design and efficiency of magnetic refrigeration systems. [ABSTRACT FROM AUTHOR]

The anomalous-Hall current injection is studied in a Hall device contacted to a lateral load circuit. This anomalous-Hall current is generated inside a Co 75 Gd 25 ferrimagnetic Hall bar and injected into a lateral load circuit contacted at the edges. The current, the voltage, and the power are measured as a function of the magnetization states, the load resistance R l , and the temperature. It is shown that (1) the resistance associated with the anomalous-Hall current flowing inside the Hall bar is that of the portion of the ferrimagnet located between the lateral contacts, (2) the role of the non-uniformity of the current due to the lateral contacts is small, (3) the maximum power efficiency of the current injection into the load circuit corresponds to the condition of the resistance matching of the two sub-circuits, and (4) this maximum power efficiency is of the order of the square of the anomalous-Hall angle. These observations are in agreement with recent predictions based on a non-equilibrium variational approach. [ABSTRACT FROM AUTHOR]

Writing and reading of magnetization states via mechanical strain are crucial for the development of ultralow-power spintronic devices. In this study, a van der Waals magnetic tunnel junction (vdW MTJ) of Fe3GaTe2/h-BN/MnBi2Te4 is constructed to explore the magnetization reversal under in-plane biaxial strains. Interestingly, the interlayer magnetic coupling of devices can be tuned to ferromagnetic and antiferromagnetic states by tensile and compressive strains, respectively. The various magnetic couplings on applied strains are analyzed using the superexchange theory. Importantly, the interlayer coupling nearly vanishes after removing external strains, ensuring the nonvolatility of magnetization reversal, resulting in the nonvolatile writing of magnetization states in the present vdW MTJ. Moreover, the tunneling magnetoresistance ratio of the device is up to −5745%, which remains −1478% even with −2% strain, showing great potential for reading the magnetization states. Therefore, this work provides an alternate avenue to write and read magnetization states in one vdW MTJ under biaxial strains. [ABSTRACT FROM AUTHOR]

We investigate the impact of non-collinear dual optical excitation on magnetization precession in a permalloy thin film using two ultrashort laser pulses. By analyzing the magnetization dynamics using time-resolved magneto-optical methods, we find that excitation with two ultrashort optical pulses introduces a long-lasting modification of the electron system, as indicated by a sizable decrease in the precession frequency and a significant increase (approximately 25%) in the decay time. Our results reveal that the observed effect strongly depends on the respective polarizations of the two excitation pulses and the time delay between the two optical pulses. Our findings indicate the occurrence of a nonlinear opto-spin effect during photoexcitation with two interfering optical pulses, which can potentially be observed in various materials and at different photon wavelengths. [ABSTRACT FROM AUTHOR]

We have fabricated the ZnFe2O4/ZnO (ZFO/ZnO) heterostructure on a silicon substrate by pulsed laser deposition technique and studied the magnetization switching by the electric field in the ZFO/ZnO heterostructure using an indigenously developed optical cantilever beam magnetometer setup. The magnetization (M) vs electric field (E) curve reveals that the magnetization of the ZFO film has been switched by an electric field applied along the thickness of the ZnO film. The saturation magnetization is found to be 28.77 MA/m from the M–E curve. The emergence of electric field-driven magnetization switching in the ZFO/ZnO heterostructure is attributed to the strain-mediated magnetoelectric coupling between the electric polarization of the ZnO film and the magnetization of the ZFO film as evidenced by the butterfly-type hysteresis behavior of magnetization with the applied electric field. However, the realization of electric field-controlled magnetization switching in the ZFO/ZnO heterostructure is regarded as a potential aspect for the fabrication of energy-efficient spintronic devices such as magnetoelectric random access memory cells, highly sensitive magnetic field sensors, magneto-logic devices, and neuromorphic devices. [ABSTRACT FROM AUTHOR]

This study explores how magnetization manipulation occurs in a flowing medium over a pipe geometry using nuclear magnetic resonance methods. In particular, the experimental conditions on radio frequency pulsing and the signal detection are studied in an ultra-low frequency regime of a few kilohertz. An analytical model of the magnetization preparation is presented, which calculates the magnetization distribution of an excited flowing segment. The effective flip angle distribution is mapped to simulate the temporal development of the magnetization in the segment. The simulation results are compared to the experimental data from a flow metering setup. As a result, the quantitative impact of the flow profile on the magnetic signal is shown. [ABSTRACT FROM AUTHOR]

Alloying heavy metals (HMs) has been an effective method for enhancing the efficiency of spin–orbit torque. In this study, we demonstrate that Pt100−xWx/Pt/Co/Ta multilayers still maintain perpendicular magnetic anisotropy after high-temperature annealing. Doping tungsten (W) into HM platinum (Pt) at the bottom of a Pt/Co/Ta multilayer significantly increases the spin Hall angle (θ S H ) and reduces the critical switching current density (Jc). The harmonic Hall test results show that the θ S H of the Pt88W12 alloy film is approximately 0.29, which is higher than that of the pure Pt film (0.15). The magnetization switching test reveals that the Jc of Pt94W6 alloy film is approximately 4.892 × 106 A/cm2, which is 51.9% lower than that of the pure Pt film. This study offers a valuable method for reducing power consumption and enhancing the efficiency of related application devices. [ABSTRACT FROM AUTHOR]

We report an enhanced magnetoelectric (ME) effect in spin–phonon coupled single-phase La1−xSmxYFe2O6 (0 ≤ x ≤ 1). The structural, electric, magnetic, and ME properties have been investigated to establish their interplay leading to magnetoelectricity. X-ray diffraction study suggests the facilitation of the P21nm phase (double perovskite lattice arrangements) formation and improved structural order due to the substitution of Sm in the lattice. Antiferromagnetic (AFM) transition ∼700 K along with a spin-reorientation transition around room temperature (RT) and below is observed in the thermomagnetic curve. The indication of short range ordering in the magnetization data in the form of a non-Griffiths-like phase (nGP) is observed. The short range ordering could be minimized along with consequent improvement in AFM ordering, due to Sm substitution. An enhanced (∼31% with respect to x = 0) RT first-order ME coupling coefficient ∼0.59 mV cm−1 Oe−1 in x = 0.75 composition is observed. The findings reported here open the door to exercise spin-reorientation transition in the spin–phonon coupled double perovskites for spintronic device applications. [ABSTRACT FROM AUTHOR]

We have investigated the magnetization reversal processes and dynamic behavior of trilayered Py(50 nm)/Pd(tPd)/Py(20 nm) nanowires with periodic width modulation as a function of spacer layer thickness tPd in the range from 0 to 10 nm and compared them with single-layer nanowires. The ferromagnetic resonance spectra show more than three modes that result from a non-uniform demagnetizing field in width-modulated nanowires. We observe that the spacer layer thickness influenced the ferromagnetic resonance spectra, which showed different numbers and values of modes and frequencies due to the different magnetization configurations for different spacer layer thicknesses. We also found that the two ferromagnetic layers are exchange-coupled for tPd = 2 nm nanowire arrays, showing the sharp switching of magnetization from the static measurements and sharp frequency jump from 13.6 to 14.7 GHz around −18 mT from the dynamic measurements. However, for tPd = 10 nm, the two layers switch at different fields, indicating a gradual decrease in magnetization as the reversal is mediated through dipolar coupling. The origin of modes is well explained from the spatial mode profiles of top and bottom magnetic layers. The dynamic responses in this spin-valve-type structure are useful for designing microwave-based spintronic devices. [ABSTRACT FROM AUTHOR]

We report an enhanced magnetoelectric (ME) effect in spin–phonon coupled single-phase La1−xSmxYFe2O6 (0 ≤ x ≤ 1). The structural, electric, magnetic, and ME properties have been investigated to establish their interplay leading to magnetoelectricity. X-ray diffraction study suggests the facilitation of the P21nm phase (double perovskite lattice arrangements) formation and improved structural order due to the substitution of Sm in the lattice. Antiferromagnetic (AFM) transition ∼700 K along with a spin-reorientation transition around room temperature (RT) and below is observed in the thermomagnetic curve. The indication of short range ordering in the magnetization data in the form of a non-Griffiths-like phase (nGP) is observed. The short range ordering could be minimized along with consequent improvement in AFM ordering, due to Sm substitution. An enhanced (∼31% with respect to x = 0) RT first-order ME coupling coefficient ∼0.59 mV cm−1 Oe−1 in x = 0.75 composition is observed. The findings reported here open the door to exercise spin-reorientation transition in the spin–phonon coupled double perovskites for spintronic device applications. [ABSTRACT FROM AUTHOR]

Spin–orbit torque (SOT) can provide efficient electrical manipulation of magnetism via applying electrical current to breaking the symmetry of damping-like torque. In the heterojunction of heavy and ferromagnetic metal, Dzyaloshinskii–Moriya interaction (DMI) is one of the key ingredients for stabilizing chiral spin structures, like chiral domain walls. Meanwhile, materials with larger charge-spin conversion rates are also highly expected for the efficient SOT. In this paper, spin–orbit torque magnetic switching is observed in the perpendicularly magnetized Pt/Co/Bi2Se3 and shows relatively high efficiency with low critical switching current density of about 5 × 105 A cm−2. The SOT efficiency and DMI in perpendicularly magnetized Pt/Co/Bi2Se3 were quantitatively investigated by electrical detection of the effective spin Hall field. The DMI constant is about 2.6 mJ m−2, and the effective spin Hall angle of Pt/Co/Bi2Se3 is about 0.14. The work also demonstrates that the Bi2Se3 layer takes the main responsibility for SOT, and the Pt/Co interface is the main source of DMI in Pt/Co/Bi2Se3 structures, which makes it possible to achieve independent optimization of DMI and SOT in the Pt/Co/Bi2Se3 structure at room temperature for the advanced application of spintronic devices. [ABSTRACT FROM AUTHOR]

Nutation and precession resonances in an antiferromagnet subjected to a dc magnetic field are investigated by employing coupled linearized inertial Landau–Lifshitz–Gilbert equations describing the dynamics of magnetizations of antiferromagnet sublattices with uniaxial magnetocrystalline anisotropy. Analytical expressions for the eigenfrequencies of such an antiferromagnet are obtained for the longitudinal and transverse directions of the external dc field and for different ranges of its strength. The effect of inertia on the values of the resonant frequencies is shown for all possible states of the antiferromagnet in both the longitudinal and transverse directions of the external field. The estimated resonant frequencies are compared with those obtained from the numerical solution of the system of undamped inertial Landau–Lifshitz–Gilbert equations for closed trajectories of sublattice magnetizations. The good agreement of both independent estimations is demonstrated. [ABSTRACT FROM AUTHOR]

We investigated the field-dependent Néel relaxation time of magnetic nanoparticles (MNPs) in an AC excitation field. Specifically, a fundamental component of the magnetization for immobilized MNPs was studied by numerical simulation while changing the frequency f and amplitude Hac of the field. From the simulation results, we clarified the Hac dependence of the effective Néel relaxation time τN,e and obtained an empirical expression for τN,e(Hac) for the first time. The expression was obtained for the cases when the angle of the easy axis of magnetization in MNPs is fixed and randomly distributed. Using the Hac dependencies of τN,e and the previously reported Brownian relaxation time τB,e, we showed that the behavior of suspended MNPs changes from Brownian-dominant to Néel-dominant when Hac increases, even when the MNP parameters are fixed, and we obtained an expression for the boundary field between them. Furthermore, we classified several types of responses for the suspended MNPs in the AC field using the magnitude relationship among τN,e(Hac), τB,e(Hac), and 1/(2πf). Finally, we experimentally verified the classification, and reasonable agreement was observed between the experiment and analysis. The results are useful for determining suitable MNP parameters and excitation conditions for various biomedical applications. [ABSTRACT FROM AUTHOR]

Spin–orbit torque (SOT) can provide efficient electrical manipulation of magnetism via applying electrical current to breaking the symmetry of damping-like torque. In the heterojunction of heavy and ferromagnetic metal, Dzyaloshinskii–Moriya interaction (DMI) is one of the key ingredients for stabilizing chiral spin structures, like chiral domain walls. Meanwhile, materials with larger charge-spin conversion rates are also highly expected for the efficient SOT. In this paper, spin–orbit torque magnetic switching is observed in the perpendicularly magnetized Pt/Co/Bi2Se3 and shows relatively high efficiency with low critical switching current density of about 5 × 105 A cm−2. The SOT efficiency and DMI in perpendicularly magnetized Pt/Co/Bi2Se3 were quantitatively investigated by electrical detection of the effective spin Hall field. The DMI constant is about 2.6 mJ m−2, and the effective spin Hall angle of Pt/Co/Bi2Se3 is about 0.14. The work also demonstrates that the Bi2Se3 layer takes the main responsibility for SOT, and the Pt/Co interface is the main source of DMI in Pt/Co/Bi2Se3 structures, which makes it possible to achieve independent optimization of DMI and SOT in the Pt/Co/Bi2Se3 structure at room temperature for the advanced application of spintronic devices. [ABSTRACT FROM AUTHOR]

Spin–orbit torque provides an efficient strategy for electric manipulation of magnetization. However, Joule heat accompanying with electron motion in the electron-mediated spin current result in unavoidable power dissipation. Moreover, the spin diffusion length in electron-mediated spin current is relatively short, preventing the transmission of spin information over long distances. Magnon-mediated spin current, without moving electrons, can be an excellent alternative to the conventional spin current. Magnon-mediated transfer torque effect has been reported in several previous works. Here, we report the magnon-mediated spin Hall magnetoresistance (SMR) and unidirectional magnetoresistance (UMR) in Pt/NiO/NiFe structures. The significant SMR and UMR were observed in the samples with the NiO thickness up to 60 nm, demonstrating the efficient transmission of magnon-mediated spin current over long distances in the NiO layer. In addition, we observed current-induced in-plane magnetization switching in the NiFe layer via the UMR measurement. These results demonstrated the possibility for developing the efficient spintronic devices operated by magnons. [ABSTRACT FROM AUTHOR]

We investigate the magnetization and the Dzyaloshinskii–Moriya interactions (DMI) in Pt/Co/Re thin films in the case of perfect interfaces and upon the introduction of intermixing on both Co interfaces. Calculations were implemented on a series of systems with a countable number of cobalt atomic layers. Remarkably, Re can introduce a DMI at the interface with cobalt and also increase the DMI at the Pt/Co interface. We demonstrate that the chiral magnetic multilayer Pt/Co/Re with a chiral spin structure can achieve a substantial DMI value, which is almost double that attained in the prototype system Pt/Co/W. We also study the DMI as a function of the Re thickness, finding the optimal thickness to maximize the DMI. When we include a disorder that cancels a contribution from all first-neighbor Co atoms in the intermixed region, we find out that intermixing at the two interfaces affects the strength of the DMI solely when introduced at the Pt/Co interface, where the DMI loses almost half of its value. On the contrary, the mixing at the Co/Re interface has very little or no effect where the calculated values were not significantly decreased as compared to the case with perfect interfaces. [ABSTRACT FROM AUTHOR]

Many natural substances in nature exhibit magnetism, which has a significant impact on human life. However, accurately predicting, analyzing, and manipulating magnetic fields requires the use of precise mathematical simulation techniques. One such method is numerical modeling with element matrices, which is crucial for simulating and analyzing complex physical models. In conventional mesh-based modeling, there is always a residual error, and the accuracy of the solution can be greatly affected by the mesh density. This work proposed a new numerical modeling theory for the field of magnetics, which is based on specially designed points within an element. With this new computational framework, the mesh-dependence feature of the element matrix can be significantly reduced, allowing for more efficient convergence to the theoretical value with minimal differences. This method can handle a wide range of extreme physical conditions in both three-dimensional and two-dimensional scenarios, which are beyond the capabilities of conventional methods, and can provide highly accurate computational solutions. The proposed method is demonstrated through the passive shielding design of a 9.4 T whole-body magnetic resonance imaging superconducting magnet, and the concept design of an extremely weak magnetic field scientific facility with cross-scale geometry was exemplified by the proposed method. [ABSTRACT FROM AUTHOR]

Spintronic terahertz (THz) emitters have been shown to be a cost-efficient source for use in time-domain THz spectroscopy. The use of external magnetic fields to control the polarity of the THz emission provides an opportunity to measure the magnetization of spintronic materials as well as shaping THz emission. Here, we demonstrate an efficient method of measuring magnetic hysteresis with material sensitivity and speed several orders of magnitude greater than typical magnetometry methods. In addition, we utilize the rapid control of material magnetization for lock-in detection in time-domain THz spectroscopy of spintronic emitters. The ability to rapidly control and measure the material magnetization on very small volumes provides an opportunity to study magnetic hetero-structures with sub-micron spatial resolution. [ABSTRACT FROM AUTHOR]

This study shows that magnetic linear dichroism (MLD) measurement has great potential for characterizing magnetic nanoparticles (MNPs) used in recently developing biomedical applications or nanoscale mechanical measurement techniques. MLD of MNP suspension reflects the orientation of the MNP. We investigated the frequency dependence of the MLD of MNP suspension under a simple AC field and the effect of the MNP size and material. Under an AC field with the frequency f, the MLD oscillated with 2f for every MNP. The amplitude and phase of this 2f-oscillation were precisely measured with a lock-in amplifier, and we showed the MLD2f frequency spectrum, a plot of real and imaginary parts of the 2f-component of MLD as a function of f. We found that the shape of the MLD2f frequency spectrum can distinguish the rotational modes of MNPs in an AC field. Therefore, this spectrum is helpful for the selection of MNPs for each technique mentioned above. We propose two model functions to fit the MLD2f frequency spectra, consistent with each rotational mode. It is shown that one of the fitting parameters τ0 is associated with the rotational Brownian relaxation time of MNP, and the other parameter β would represent the distribution of the anisotropy energy. The frequency dependence of MLD will provide precise insights into the magnetization and orientational dynamics of the MNP in liquid. [ABSTRACT FROM AUTHOR]

Using a molecular beam epitaxy technique, we experimentally demonstrate a multiferroic heterostructure consisting of metastable ferromagnetic Co 3 Mn on piezoelectric Pb(Mg 1 / 3 Nb 2 / 3 )O 3 –PbTiO 3 (PMN-PT). Inserting a 2-nm-thick Fe layer between Co 3 Mn and PMN-PT(001) allows the formation of bcc Co 3 Mn layers even at an extremely low growth temperature of ∼ 80 ° C. Upon increasing this temperature to 200 ° C, a bcc Co 3 Mn/Fe/PMN-PT(001) multiferroic heterostructure with a relatively large saturation magnetization of ∼ 1680 kA/m and an atomically flat interface is obtained, resulting in an obvious converse magnetoelectric (CME) effect. The large CME effect originates mainly from the strain-induced modulation of the magnetic anisotropy energy, supported by the first-principles calculations. [ABSTRACT FROM AUTHOR]

We demonstrate experimentally and numerically the control of magnetization circulation of the closure domain state in thin permalloy squares divided diagonally into four dipolar-coupled isosceles triangles. The control over the magnetization circulation was achieved by the mutual application of a suitable external in-plane magnetic field and interaction with a magnetic force microscopy (MFM) tip. Numerical simulations confirm that the proposed switching protocol is valid for the broad range of MFM tips. Experiments performed on four diagonally cut squares show that this method is robust against slight imperfections in the fabrication process. Moreover, by varying the polarity of the applied field and the direction of the MFM scanning, proper symmetry response of the switching method is observed. [ABSTRACT FROM AUTHOR]

This Tutorial article focuses on magnetic phenomena and material systems that have gained significant importance since the original development of mumax3, but are challenging to simulate for users who rely solely on the originally provided examples. Alongside the physical background, we provide hands-on examples of advanced magnetic systems, including detailed explanations of complete mumax3 input files (13 in total, often showing different ways to achieve things), and highlighting potential pitfalls where applicable. Specifically, we explore two approaches to incorporate spin–orbit torques in mumax simulations, considering the trade-off between versatility and speed. We also examine complex multilayer material stacks, including synthetic antiferromagnets, demonstrating different implementation methods that again vary in speed, versatility, and realism. A key criterion for selecting the optimal simulation strategy is its suitability for modeling systems where the magnetization varies significantly in the third dimension. The material covered in this Tutorial paper includes content developed for the mumax3 workshop presented during the summer of 2020 within the context of the IEEE online spintronics seminar, along with additional new topics. Throughout the explanations, we ensure broad applicability beyond specific examples. [ABSTRACT FROM AUTHOR]

We numerically demonstrate that a pure time-harmonic bias AC current of a specific amplitude τ f and angular frequency ω f can excite the chaotic magnetization dynamics in a Josephson-like antiferromagnetic (AFM) spin Hall oscillator (SHO) with biaxial magnetic anisotropy of an AFM layer. The nature of such a stochastic generation regime in a Josephson-like AFM SHO could be explained by the random hopping of the working point of the SHO between several quasi-stable states under the action of an applied AC current. We reveal that depending on the ω f / τ f ratio several stochastic generation regimes interspersed with regular generation regimes can be achieved in an AFM SHO, which can be used in spintronic random signal sources and various nano-scale random signal devices, including the spintronic p-bit device considered in this work. The obtained results are important for the development and optimization of spintronic devices capable of generating and processing (sub-)THz-frequency random signals, which are promising for ultra-fast probabilistic computing, cryptography, secure communication, etc. [ABSTRACT FROM AUTHOR]

A polycrystalline ZnO film is grown on a silicon substrate by the pulsed laser deposition method, and the electric field-induced magnetization in ZnO using an optical cantilever beam magnetometer setup is studied. The magnetization vs bipolar dc electric field measurements reveal the occurrence of magnetization switching in the ZnO film. The magnetization switching in the presence of an electric field is ascribed to the converse magnetoelectric (ME) coupling that takes place between the electrical and the magnetic order parameters existing in the ZnO film. We have found the strain-driven magnetization change as evidenced by the butterfly shape of the magnetization vs the electric field curve. A saturation magnetization of 13.31 MA/m is obtained. Moreover, a significant value of the ME coupling coefficient (α) (1.61 × 10−7 s/m) has also been reported in this article. The emergence of electric field-induced magnetization in a single polycrystalline ZnO film is regarded to be a very promising aspect in designing high-density energy-efficient spintronic and different multifunctional devices. [ABSTRACT FROM AUTHOR]

We have conducted the study of structural, magnetic, magnetothermal, and magnetoelastic properties of four rare-earth compounds: Gd4.5Tb0.5Si2Ge2, Gd4TbSi2Ge2, Gd4.4Tb0.5Ti0.1Si2Ge2, and Gd3.9TbTi0.1Si2Ge2 in the vicinity of magnetically induced phase transitions. We demonstrate that the introduction of Ti into the rare-earth sublattice separates the structural and magnetic phase transitions and changes the order of magnetic phase transition from type I to II, while preserving high values of magnetocaloric effect (MCE). Additionally, incorporating a small quantity of Tb enables the creation of compounds with enhanced MCE values over a specific temperature range of 240–290 K. The observed phenomena can be attributed to the combined effects of forced magnetization and alteration of magnetic susceptibility during the structural phase transition that accompany the magnetic phase changes in these compounds. [ABSTRACT FROM AUTHOR]

We demonstrate the possibility of a coupling between the magnetization direction of a ferromagnet and the tilting angle of adsorbed achiral molecules. To illustrate the mechanism of the coupling, we analyze a minimal Stoner model that includes Rashba spin–orbit coupling due to the electric field on the surface of the ferromagnet. The proposed mechanism allows us to study magnetic anisotropy of the system with an extended Stoner–Wohlfarth model and argue that adsorbed achiral molecules can change magnetocrystalline anisotropy of the substrate. Our research aims to motivate further experimental studies of the current-free chirality induced spin selectivity effect involving both enantiomers. [ABSTRACT FROM AUTHOR]

High-temperature superconducting (HTS) trapped field magnets can generate and maintain stable, high magnetic fields without requiring external power supplies. Recently, HTS-stacked ring magnets have garnered significant attention due to their flexible geometry, robust mechanical strength, and proven trapped field performance. In this study, we examine the magnetization characteristics of HTS-stacked ring magnets and observed a trapped field higher than the applied field during field cooling magnetization. We also observed that by inserting HTS stacks into the hollow cavity of the HTS-stacked rings, the center field ceased to exhibit an increased center field. Our analysis revealed that the unique induced current distribution and the penetration sequence are the underlying causes. Inspired by the investigation results, we explored deeper into the magnetization properties and identified that a final trapped field higher than the applied field can be achieved through proper design and magnetization of the HTS-stacked ring magnets. However, even though the trapped central field experiences an increase, this does not translate into an increment in the total trapped flux. Instead, a redistribution of the flux is observed. These findings hold significant implications for the design and application of superconducting magnets. [ABSTRACT FROM AUTHOR]

The magnetoelectric (ME) response of laminated composites consisting of BaFe12O19 and Pb(Zr,Ti)O3 ceramics is systematically investigated. A butterfly-shaped curve of a magnetoelectric coefficient emerges in both three-layer and multilayer composites. We show that the appearance of a 7 ppm residual strain in the BaFe12O19 layer after magnetization is the main reason for this special curve. We also observe the self-biasing effect of the composites and a maximum ME response from 0.6 to 5 mV/(Oe cm) in laminated composites with magnetic and ferroelectric layers of different thicknesses that can be measured at a zero-bias magnetic field. The repeatable and stable maximum and minimum values of the magnetoelectric coefficient can be obtained under periodically applied biasing magnetic fields, which is important for a practical device application. An electric-field control of ferromagnetism, evidenced by a 17%–19% enhancement in the magnetization of the BaFe12O19 layer after Pb(Zr,Ti)O3 is polarized, is observed in the composites, implying potential applications in memory devices for the composites. Our work indicates that both magnetic field-controlled polarization and electric-field-controlled magnetization exist in BaFe12O19/Pb(Zr,Ti)O3 laminated composites. [ABSTRACT FROM AUTHOR]

In this work, we shed light on the mechanism behind the complexity of the anomalous Hall effect (AHE) in the rare earth-transition metal (RE-TM) compound. To achieve a comprehensive picture, we first theoretically investigate the pure elemental metals and observe that the AHE of RE Gd is negative while that of TM Co is positive. We then investigate magnetic properties and AHE behavior for two typical cases of TM-rich and RE-rich compositions that correspond to GdCo5 and GdCo3 alloys, respectively. The observation that net magnetization is not a decisive factor in assessing the AHE value is consistent with recent claims. Besides, our investigations reveal a significant role of the Gd sublattice to the AHE. The reduction AHE signal under a high-applied field is attributed to the counteraction between the positive and negative AHC contributions when the TM and RE sub-moments are aligned parallel. On a bright note, our new findings can be successfully employed to unravel two types of aberrant humps of AHE signals near compensation temperature. [ABSTRACT FROM AUTHOR]

Replacement of the heteroatom from Si to Ge has a strong influence on the luminescence properties of a series of hybrid, sandwich-type K5[Ln(α-GeW11O39)(C20H22Br2N2O4)]·14H2O (1Ge-Ln, Ln = Sm to Lu) anions. Interestingly, the Gd and Yb derivatives retain their ability to display slow relaxation of magnetisation. [ABSTRACT FROM AUTHOR]

Four novel Co(II) coordination compounds 1–4 of the general formula [Co(Ln)2][Co(NCY)4]·mCH3CN (where Ln are tridentate ligands L1 = 2,6-bis(1-hexyl-1H-benzimidazol-2-yl)pyridine for 1 and 2; L2 = 2,6-bis(1-octyl-1H-benzimidazol-2-yl)pyridine for 3; L3 = 2,6-bis(1-dodecyl-1H-benzimidazol-2-yl)pyridine for 4, Y = O for 1, 3, and 4 and Y = S for 2; m = 0 for 1 and 3, m = 0.5 for 2 and m = 2 for 4) were prepared and characterised. The molecular structures of all four compounds consist of the hexacoordinate complex cation [Co(Ln)2]2+ and tetracoordinate complex anion [Co(NCY)4]2−, with distorted octahedral and tetrahedral symmetry of coordination polyhedra, respectively. The electronic structures of all compounds feature an orbitally non-degenerate ground state well-separated from the lowest excited state, which allows the analysis of the magnetic anisotropy by the spin Hamiltonian model. ZFS parameters, derived from both CASSCF-NEVPT2 calculations and magnetic data analysis, indicate that tetrahedral anions [Co(NCY)4]2− exhibit small axial parameters ‖D‖ spanning the range of 2.2 to 7.7 cm−1, while octahedral cations [Co(Ln)2]2+ display significantly larger ‖D‖ parameters in the range of 37 to 95 cm−1. For 1–3, the Fourier-transform infrared magnetic spectroscopy (FIRMS) revealed a reasonable transmission with a magnetic absorption around the expected value for the ZFS accompanied by features allowing to identify phonon frequencies and simulate spin-phonon couplings. Dynamic magnetic investigations unveiled the field-induced slow relaxation of magnetisation, with maximal relaxation times (τ) of 92(2) μs for 2 at 2 K and BDC = 0.3 T. The temperature evolution of τ was analysed using a combination of Orbach, direct and Raman relaxations (Ueff = 8(1) K (5.6 cm−1)) or Orbach, direct and spin-phonon induced relaxations (Ueff = 10.3(9) K (7.2 cm−1)). The rest of the complexes, namely 1, 3, and 4 show field-induced slow relaxation of magnetisation with τ smaller than 16 μs. [ABSTRACT FROM AUTHOR]

Magnetic Permeability Perturbation testing (MPPT) has the advantage of high sensitivity for deeply buried defects in steel pipes. However, in complex working conditions, variations in the partial wall thickness of the pipe can affect the defect detection results. The paper discusses the influence mechanism of uneven wall thickness on the MPPT of internal defects on steel pipes and analyzes the magnetic field distribution caused by uneven wall thickness which influences on the magnetic permeability perturbation (MPP) of internal defects. The MPP is enhanced at the thinning wall and weakened at the thickening wall. The effect of uneven wall thickness on MPPT signals is confirmed through simulation and experiment. The signal of defects in thinning wall is enhanced, while the signal of defects in thickening wall is weakened. The greater the wall thickness variation, the degree of signal distortion is more significant. Experimental results show that uneven wall thickness has an effect on the detection of the defects with different depths. Finally, a method using deep saturation magnetisation is proposed to mitigate the inconsistent signals caused by uneven wall thickness. The findings will contribute to quantitative evaluation of defects in MPPT. [ABSTRACT FROM AUTHOR]

The sol-gel self-combustion technique was applied to form Cd–Co-based La-doped (Cd 0.5 Co 0.5 La x Fe 2-x O 4) spinel ferrite nanoparticles. A series of six samples was synthesized by varying lanthanum content from x = 0.00 to 0.20. The structural characteristics of the prepared nanoparticles were carried out using X-ray diffraction (XRD) analysis. The (311) plane verified that the prepared nanomaterials are in the spinel phase in all observed XRD patterns. The crystallite size for each sample was determined using the Scherrer formula found in the 8.7–17.8 nm range, which is well correlated with the SSP model. The crystallite size decreased while the lattice constant increased from 8.38 to 8.45 Å with increasing La-content. The increasing trend in the bulk density and X-ray density has been analyzed with the effects of La3+ contents. In Fourier-transform infrared spectroscopy (FTIR), the high-frequency absorption band (υ 1) was found from 522.15 to 541.06 cm−1, whereas the low-frequency band (υ 2) varied from 419.80 to 414.31 cm−1. The surface morphology was carried out by scanning electron microscope (SEM), which positively correlated with XRD analysis. Impedance analyzer (IA) assisted in observing the variations in complex dielectric properties of the compound in the frequency range from 1 MHz to 3 GHz. The dielectric constant and impedance plots depicted that the nano ferrites have good dielectric properties in low-frequency regions due contribution of polarization. While conduction can be made possible in the high-frequency areas as observed through AC conductivity. The electric modulus revealed the relaxation phenomenon at high frequency due to the hopping of electrons at the octa and tetrahedral sites. The magnetic properties were investigated to study the impact of La3+ ion under the applied magnetic field from −15 to 15 kOe. The saturation magnetization, and magnetic remanence were found from 40.6 to 27.7 emu/g and 19.6 to 2.7 emu/g, respectively. The synthesized nanoparticles can be utilized for microwave applications and magnetic storage devices. [ABSTRACT FROM AUTHOR]

An experimental and theoretical investigation of the magnetic properties of Ti-doped barium hexaferrite (BaM) is conducted. Polycrystalline samples of BaFe 12 − x Ti x O 19 with x ≤ 0.2 were synthesized using the solid-state reaction method. X-ray diffraction (XRD) analyses, along with Rietveld refinement, confirmed the presence of BaFe 12 O 19 as the predominant BaM phase and a minor amount of hematite in all samples. Structural analysis revealed a slight increase in lattice parameters a and c for x = 0. 2. A result mostly related to the preferential occupation of Ti 4 + ions at the 4f 2 and 12k sites, coupled with the reduction of Fe3＋ ions to Fe2＋. It was also found that the magnetic response of samples is affected by Ti 4 + substitution. Saturation magnetization slightly decreased from ∼ 45 (x = 0) to ∼ 44 emu/g (x = 0.2), the anisotropy constant from ∼ 4. 08 × 105 to ∼ 4. 06 × 105 erg/g 2 , while coercivity slightly increased from ∼ 2456 to ∼ 2468 Oe, and the anisotropy field from ∼ 18.2 to ∼ 18.6 kOe. The magnetic features of the samples were analyzed in terms of a proposed model based on the mean-field theory. Results indicated that the substitution of Ti 4 + ions resulted in a decrease in the magnetic moment of the 2b sublattice. Such behavior is influenced by its closest neighboring sites 12k and 4f 2 sublattices, which are the preferred occupancy sites for the Ti 4 + cations. [ABSTRACT FROM AUTHOR]

Inter-granular Sn particles affect transport and magnetic properties both in the normal and superconducting states of polycrystalline GdBa2Cu3O7−δ (GdBCO) superconductors drastically. Normal state resistivity at 300 K increases ~ 18.0 times as the concentration of Sn is increased. An unusual upturn in resistivity as a function of temperature curve with a dip is observed in GdBCO with 3.0 wt% of Sn in which suppression of superconducting phase transition has been observed. Current-voltage (IV) curves below Tc exhibit nonlinear features in composites of GdBCO and Sn. Magnetization (M) as a function of magnetic field (H) curves at 2.0 –20.0 K in GdBCO shifts strongly with the addition of 1.0 wt% Sn. We have extracted irreversible magnetization, lower critical field (Hc1) and magnetic critical density (Jcm) as a function of H at several T. The maximum pinning force density is 0.4 GN/m3 in GdBCO which is reduced in the Sn added GdBCO. [ABSTRACT FROM AUTHOR]

In the present investigation, magnetic and dielectric properties of solid‐solution formed between the YFeO3 with the similar crystal structure of other oxide materials are focused on. Orthorhombic crystal structure of YFeO3 (YFO), Sr2Bi4Ti5O18 (SBT), and ZnSnO3 (ZS) nanomaterials are considered to prepare the solid solutions at 1150 °C/3 h. YFO and solid solutions exhibit the orthorhombic crystal structure, which is conformed through Rietveld refinement using X‐Ray powder diffraction pattern. The decreased average grain size is observed for the solid solution (3.0 μm for YFO and ZS and 2.6 μm for YFO and SBT) when compared to YFO (3.4 μm) through scanning electron microscopy. Oxidation state of each atom/ion/element present in the YFO and solid solutions are conformed through X‐Ray photoelectron spectroscopy studies. The solid solution formed between the YFO and SBT exhibits high magnetization value (2.92 emu g−1) and high coercive filed (67.5 Oe) when compared to solid solution formed between the YFO and ZS (magnetization value = 2.48 emu g−1, and coercive filed = 46.4 Oe) and YFO (magnetization value = 1.91 emu g−1, and coercive filed = 61.8 Oe). High dielectric permittivity (εr), low dielectric loss (tan δ), and low conductivity are observed for the solid solution formed between the YFO and SBT, when compared to other materials in this study. [ABSTRACT FROM AUTHOR]

Zero-field magnetization switching (ZFS) driven by current-induced spin–orbit torque (SOT) holds significant importance in spintronic applications. The introduction of a lateral asymmetric structure (LAS) through oblique deposition proves to be an effective strategy for breaking inversion symmetry, thereby enabling SOT-driven ZFS. However, the coexistence of wedge thickness structure and slanted columnar microstructure in the obliquely deposited films poses challenges in distinguishing their respective effects. In this study, we conducted a comparative investigation of the perpendicular magnetic properties and current-induced switching in W/Co40Fe40B20/MgO films by oblique sputtering of the W underlayer at a fixed tilting angle and at two opposite tilting angles with its wedge thickness compensated. We have found that the perpendicular magnetic properties of the Co40Fe40B20 layer are significantly altered at large tilting angles, irrespective of whether the W wedge thickness is compensated. Notably, at a tilting angle of 50°, ZFS is realized for both the conventional oblique sample and the compensating oblique sample, with the switching polarity contingent on the final tilting direction of the W layer. We have identified a gradient in perpendicular magnetic anisotropy in these samples, attributed to the laterally varying roughness associated with the slanted columnar microstructure of the W underlayer. This study underscores the dominant role of microscopic LAS in obliquely deposited films in breaking SOT symmetry. Our research sheds light on the impact of the slanted columnar microstructure on the magnetic and magneto-transport properties of films, offering valuable insights for advancing spintronic device research. [ABSTRACT FROM AUTHOR]

Two novel Ce(III) metal organic frameworks (MOFs) with formulas [Ce(5Meip)(H-5Meip)]nGR-MOF-17 and [CeCl(5Meip)(DMF)]nGR-MOF-18 (5Meip = 5-methylisophthalate, DMF = N,N-dimethylformamide) have been synthesized, forming 3-dimensional frameworks. Magnetic measurements show that both compounds present field-induced slow magnetic relaxation under a small applied dc field. For GR-MOF-17, the temperature dependence of relaxation times is best described by a Raman mechanism, whereas for GR-MOF-18, relaxation occurs through a combination of Raman and local-mode pathways. Moreover, when avoiding short Ce⋯Ce interactions by magnetic dilution in GR-MOF-17@La and GR-MOF-18@La, only the local-mode mechanism is responsible for magnetic relaxation. Photophysical studies show the occurrence of ligand-centred luminescence in both compounds and phosphorescence emission at low temperature for GR-MOF-17. [ABSTRACT FROM AUTHOR]

We study the process of controlling the states of a magnetic memory cell by a pulsed magnetic field. The magnetization dynamics of such a system is described by the Landau-Lifshitz equation. We find the optimal parameters of time dependence, amplitude and duration of magnetic field pulses created by currents in the control system, which provide a fast inertialess process of switching the magnetization of the functional element of the cell. [ABSTRACT FROM AUTHOR]

Enhancing magnetic data is often complicated due to the non‐vertical orientation of the geomagnetic field and the orientation of remanent source magnetization. The complication can be reduced by reducing the data to the pole (mathematically making the geomagnetic field vertical), but this reduction process is problematic. The analytic‐signal amplitude can be used to enhance the edges of two‐dimensional sources without a reduction to the pole. However, the shape of the analytic‐signal amplitude is weakly dependent on the magnetization direction for grid data. This study presents an improved technique, namely the tilt angle of the analytic‐signal amplitudes of the horizontal gradient of the vertical integral. This quantity is also only weakly dependent on the magnetization direction and outlines the edges as well or somewhat better than other methods. It also implicitly involves second derivatives of the magnetic field, and we use synthetic data to demonstrate that noise is not amplified as much as it is when using other edge enhancement techniques that implicitly use second derivatives. A dataset of the Apiaí Terrane, Brazil, shows good lateral continuity of features compared with other edge‐enhancement methods, and subtle features like faults are easier to identify in the images generated by our new method. Upward continuation of the field, which is normally required, was not necessary to reduce the impact of noise on this field example. [ABSTRACT FROM AUTHOR]

The absence or presence of a lunar paleomagnetosphere is important because it bears directly on the volatile content of the regolith and exploration targets for Artemis and other missions to the Moon. Recent paleointensity study of samples from the Apollo missions has readdressed this question. Multiple specimens from a young 2-million-year-old glass shows a strong magnetization compatible with that induced by charge-separation in an impact plasma, whereas paleointensities of single crystals yield evidence for null magnetizations spanning 3.9 to 3.2 Ga. Together, these data are consistent with an impact mechanism for the magnetization of some lunar samples, and absence of a long-lived lunar core dynamo and paleomagnetosphere recorded in other samples. Here, we present a dataset that allows researchers to examine replicates of these measurements. For the glass, we present data from specimens that fail standard paleointensity selection criteria but nevertheless imply a complex, changing magnetic field environment. For the single crystals, the replicate measurements further illustrate the initial zero magnetization state of these materials. [ABSTRACT FROM AUTHOR]

LaFe0.5Cr0.5O3 was synthesized using the sol–gel method and subsequently annealed at 750∘C and 900∘C. Magnetization curves and Mössbauer spectra were employed to evaluate the macroscopic magnetism of the samples at 300K. The results showed that coercivity increased with higher annealing temperatures. Notably, magnetic measurements of the LFCO-900 sample revealed an unusual trend in the M–T curve between 50K and 150K, likely due to annealing-induced changes in magnetic entropy. Annealing temperature significantly influences LFCO’s magnetic properties. Monte Carlo simulations modeled magnetization’s temperature dependence in disordered systems under varying magnetic field strengths, aligning with observations in LFCO-750. These insights are crucial for furthering understanding of perovskite materials’ physical properties and for enhancing the magnetic entropy effect in such systems, thereby increasing their practical application potential. [ABSTRACT FROM AUTHOR]

Context. Observations of blue-shifted X-ray absorption lines indicate the presence of wind from the accretion disc in X-ray binaries. Magnetohydrodynamic (MHD) driving is one possible wind-launching mechanism. Recent theoretical developments have made self-similar magnetic accretion-ejection solutions much more generalised, showing that wind can be launched at a much lower magnetisation than the equipartition value, which had previously been the only possibility. Aims. In this work, we model the transmitted spectra through MHD-driven photoionised wind models with different levels of magnetisation. We investigate the possibility of detecting absorption lines by upcoming instruments, such as XRISM and Athena. We investigate the robustness of the method of fitting asymmetric line profiles by multiple Gaussians. Methods. We used the photoionisation code XSTAR to simulate the transmitted model spectra. To cover the extensive range of velocity and density of the wind spanned over a large distance (∼105 gravitational radii), we divided the wind into slabs following a logarithmic radial grid. Fake observed spectra are finally produced by convolving model spectra with instrument responses. Since the line asymmetries are apparent in the convolved spectra as well, this can be used in future XRISM and Athena spectra as an observable diagnostic to fit for. We applied some amount of rigor in assessing the equivalent widths of the major absorption lines, including the Fe XXVI Lyα doublets, which will be clearly distinguishable thanks to the superior quality of future high-resolution spectra. Results. Disc magnetisation stands as another crucial MHD variable that can significantly alter the absorption line profiles. Pure MHD outflow models at low magnetisation are dense enough to be observed by the existing or upcoming instruments. Therefore, these models can serve as simpler alternatives to MHD-thermal models. Fitting with multiple Gaussians is a promising method for handling asymmetric line profiles, as well as the Fe XXVI Lyα doublets. [ABSTRACT FROM AUTHOR]