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Exploring paramagnetic salts with weak magnetic interactions and large saturation magnetic moments is of great significance in the field of cryogenic magnetic refrigeration. In this article, the first-principles calculation is performed to predict the magnetocaloric effect (MCE) of La-transition metal-based double nitrate hydrated salts. Through the comparison of the calculation results, La2Mn3(NO3)12·24H2O (LMnN) is chosen for further research on cryogenic magnetic refrigeration. The magnetic measurements reveal a weak antiferromagnetic interaction and large saturation magnetic moment of 4.95 μB of LMnN, which are consistent with theoretical calculation results. In addition, the maximum magnetic entropy change of LMnN is calculated to be 26.61 J kg−1 K−1 under a magnetic field change of 7 T at 2.5 K, which is greater than that of another double nitrate hydrated salts La2Co3(NO3)12·24H2O (LCoN). Excellent MCE verifies the rationality of first-principles calculation and suggests that LMnN is a promising hydrated paramagnetic salt for cryogenic magnetic refrigeration. [ABSTRACT FROM AUTHOR]

Iron germanide (FeGe) emerges as a promising magnetic alloy for spintronics and high-density data storage, owing to its distinctive magnetic properties and compatibility with existing fabrication techniques. This compatibility enables the synthesis of customized FeGe nanocylinders characterized by chirality, where their magnetization asymmetrically twists. Within specific size parameters, these nanocylinders can accommodate skyrmions—swirling magnetic structures with significant implications for information storage and processing technologies. This study investigates the response of FeGe nanocylinders to external magnetic fields, focusing on how their magnetic properties vary with dimensions (diameter and length). Specifically, we analyze the impact of length on the pseudo-static properties of short FeGe nanocylinders and examine the average topological charge and remanence states across different aspect ratios. Our investigation underscores the relationship between chirality and diverse magnetization states in four types of nanocylinders with varying aspect ratios. This comprehensive analysis elucidates the connection between nanocylinder magnetic states and the average topological charge—a critical factor in advancing ultra-low-energy data storage and logic devices. [ABSTRACT FROM AUTHOR]

Clock transitions (CTs) in spin systems, which occur at avoided level crossings, enhance quantum coherence lifetimes T2 because the transition becomes immune to the decohering effects of magnetic field fluctuations to first order. We present the first electron-spin resonance characterization of CTs in certain defect-rich silica glasses, noting coherence times up to 16 μs at the CTs. We find CT behavior at zero magnetic field in borosilicate and aluminosilicate glasses, but not in a variety of silica glasses lacking boron or aluminum. Annealing reduces or eliminates the zero-field signal. Since boron and aluminum have the same valence and are acceptors when substituted for silicon, we suggest the observed CT behavior could be generated by a spin-1 boron vacancy center within the borosilicate glass, and similarly, an aluminum vacancy center in the aluminosilicate glass. [ABSTRACT FROM AUTHOR]

Distinguishing different antiferromagnetic domains by electrical probes is a challenging task, which in itinerant compounds can be achieved, e.g., via the anisotropic magnetoresistance. Here, we demonstrate that in insulators, the anisotropic magnetocapacitance can be exploited for the same purpose. We studied the magnetic field dependence of the dielectric response in BiFeO3, one of the few room-temperature multiferroics. We observed a sizeable dielectric anisotropy upon the rotation of the modulation vector of the antiferromagnetic cycloid in the plane normal to the rhombohedral axis. Importantly, this anisotropy is characteristic of the cycloidal mono-domain state even in zero magnetic field, thus facilitating the determination of the antiferromagnetic domain population. This approach can be utilized to electrically distinguish between antiferromagnetic domains even in complex magnets, such as modulated spin structures, via the magnetodielectric coupling. [ABSTRACT FROM AUTHOR]

We present a study on the static magnetic properties of individual GaAs- Fe 33 Co 67 core–shell nanorods. X-ray magnetic circular dichroism combined with photoemission electron microscopy and scanning transmission x-ray microscopy were used to investigate the magnetic nanostructures. The magnetic layer is purposely designed to establish a magnetic easy axis neither along the nanostructure's long axis nor perpendicular to it to promote a 3D magnetic helical configuration on the tubular surface. In practice, two types of magnetic textures with in-plane magnetization were found inside the nanostructures' facets: magnetic domains with almost longitudinal or almost perpendicular magnetization with respect to the axis of the tube. We observe that a magnetic field applied perpendicular to the long axis of the nanostructure can add an azimuthal component of the magnetization to the previously almost longitudinal magnetization. [ABSTRACT FROM AUTHOR]

Distinguishing different antiferromagnetic domains by electrical probes is a challenging task, which in itinerant compounds can be achieved, e.g., via the anisotropic magnetoresistance. Here, we demonstrate that in insulators, the anisotropic magnetocapacitance can be exploited for the same purpose. We studied the magnetic field dependence of the dielectric response in BiFeO3, one of the few room-temperature multiferroics. We observed a sizeable dielectric anisotropy upon the rotation of the modulation vector of the antiferromagnetic cycloid in the plane normal to the rhombohedral axis. Importantly, this anisotropy is characteristic of the cycloidal mono-domain state even in zero magnetic field, thus facilitating the determination of the antiferromagnetic domain population. This approach can be utilized to electrically distinguish between antiferromagnetic domains even in complex magnets, such as modulated spin structures, via the magnetodielectric coupling. [ABSTRACT FROM AUTHOR]

EuB6, as a magnetic Weyl semimetal, has attracted much attention in recent years due to its rich intriguing physical properties, especially the colossal negative magnetoresistance (CNMR) exceeding −80% and the topological phase transition. Yet, the underlying mechanism of the CNMR in EuB6 is still controversial. In this work, the CNMR with a maximum value of −88.4% and Hall resistivity without linear dependence on the magnetic field are both observed to indicate the existence of a weak ferromagnetic order below 50 K. The effective carrier concentration can be modulated by both temperatures and external magnetic fields. Moreover, the angle-resolved photoelectron spectroscopy results demonstrate the gradual band splitting and crossing near the Fermi level below 15 K, and the field-dependent Kelvin probe force microscope results confirm the field-induced variation of the Fermi level at different temperatures. Furthermore, by integrating those results with the monotonic increment relationship between the effective carrier concentration and the field-induced magnetization ratio, it is concluded that the magnetic field-induced topological phase transition is the main mechanism for the CNMR in EuB6, which is helpful to understand the exotic transport properties in magnetic topological materials. Our findings provide a route for exploring and manipulating the topology-related transport properties via the external magnetic field in other systems with strong correlation between magnetism and topological states. [ABSTRACT FROM AUTHOR]

The "direct" spin Hall (DSH) effect has been intensively studied to manipulate the magnetic state in spin–orbit torque magnetic random access memory. Meanwhile, its reciprocal phenomenon, known as the "inverse" spin Hall (ISH) effect, has been studied as a method to read the magnetic state of a magnetic element in a magnetic read head sensor and magnetoelectric spin–orbit logic device. This work studies a magnetic field sensing device structure in which the DSH effect is used for reading the magnetic state in a ferromagnetic (FM)/topological insulator (TI) heterostructure. We found that while the output of our DSH sensing device is consistent with that based on the ISH effect, the spin Hall angle calculated from its magnitude is colossal (θSH ∼ 164) and significantly higher than that (θSH ∼ 3.5) obtained from the second harmonic measurement. Our findings show that the giant DSH and ISH effects in TI-based heterostructures are useful for realizing next-generation magnetic read head device and have important implications for engineering topological quantum materials with high spin Hall performance. [ABSTRACT FROM AUTHOR]

We propose a quantum technology for producing chiral systems from multilayer nanostructures based on quantum Stern–Gerlach effects. Using the example of multilayer systems with non-magnetic metals, such as [Bi(Ag)–Al2O3] N , we demonstrate that depending on the relative orientation of the substrate, the magnetic field, and the beam of atoms from the sputtered material, several separate extended regions (films) grow on the substrate. In these regions, stable optical unidirectional anisotropy emerges, with the orientation of the axis varying across different regions. Our findings reveal that the resulting anisotropy is influenced by the interaction of atomic moments within the metal film. Remarkably, external magnetic and electric fields, as well as thermal annealing, fail to destroy the unidirectional anisotropy in the prepared structures. Thus, these structures exhibit highly correlated behavior. [ABSTRACT FROM AUTHOR]

Plasmon-induced transparency (PIT) metasurfaces have emerged as a promising platform for applications in ultrasensitive detection and slow-light devices. The active control of PIT metasurfaces is particularly crucial for advancing these applications. In this study, we integrate the phase change material Ge2Sb2Te5 (GST) into the structural design of a polarization-independent metasurface, enabling the experimental realization of ultra-large depth modulation of PIT peaks. This was achieved through direct thermal activation of the sample and laser-induced multilevel nonvolatile modulation, with a modulation range extending from 0% to 35.2%. The underlying mechanism for this significant modulation depth is attributed to the suppression of magnetic resonance by the GST phase transition, which is elucidated through analyses of multipolar scattering power, electric field distribution, and magnetic field distribution. The proposed terahertz metasurface presents a pathway for the development of optical switches and slow-light devices, with potential applications in advanced photonic systems. [ABSTRACT FROM AUTHOR]

EuB6, as a magnetic Weyl semimetal, has attracted much attention in recent years due to its rich intriguing physical properties, especially the colossal negative magnetoresistance (CNMR) exceeding −80% and the topological phase transition. Yet, the underlying mechanism of the CNMR in EuB6 is still controversial. In this work, the CNMR with a maximum value of −88.4% and Hall resistivity without linear dependence on the magnetic field are both observed to indicate the existence of a weak ferromagnetic order below 50 K. The effective carrier concentration can be modulated by both temperatures and external magnetic fields. Moreover, the angle-resolved photoelectron spectroscopy results demonstrate the gradual band splitting and crossing near the Fermi level below 15 K, and the field-dependent Kelvin probe force microscope results confirm the field-induced variation of the Fermi level at different temperatures. Furthermore, by integrating those results with the monotonic increment relationship between the effective carrier concentration and the field-induced magnetization ratio, it is concluded that the magnetic field-induced topological phase transition is the main mechanism for the CNMR in EuB6, which is helpful to understand the exotic transport properties in magnetic topological materials. Our findings provide a route for exploring and manipulating the topology-related transport properties via the external magnetic field in other systems with strong correlation between magnetism and topological states. [ABSTRACT FROM AUTHOR]

Reservoir computing can be implemented in a variety of systems beyond standard CMOS technology. Here, we describe a scheme that relies on a magnetic reservoir consisting of an antidot array, motivated by earlier experiments on ring arrays. We show that antidot lattices can be used as reservoirs much in the same way as ring arrays. We describe geometries in which smaller magnetic fields are needed to induce emergent magnetic patterns in the reservoir, a prerequisite for its use in reservoir computing. High-resolution magnetic imaging of these patterns shows entirely different domains and domain walls, despite the fact that the macroscopic magnetic signal behaves very similarly in both types of reservoirs. [ABSTRACT FROM AUTHOR]

Using purely electrical methods to manipulate magnetic property poses a significant obstacle in the development of advanced information technology. Multiferroic materials, distinguished by their magnetoelectric (ME) effect, offer a promising way to overcome this challenge by enabling the electric control of magnetic ordering or magnetization. Here, we have synthesized Cu3Mo2O9 single crystals and investigated the anisotropic ME effect within the quasi-one-dimensional spin system. The simultaneous occurrence of ferroelectric (FE) polarization and dielectric anomaly at the Néel temperature (TN) of ∼7.9 K suggests the presence of spin-driven FE property in Cu3Mo2O9. The phase transition temperatures undergo a shift toward lower values for H//c and remain constant for H//a and H//b, indicating anisotropic ME effect. The ME effect demonstrates nonlinear behavior as the magnetic field increases. Near a critical point (T = 7 K and μ0H = 5.6 T), a giant magnetodielectric coupling parameter reaching 374% is observed for H//c, which can be ascribed to the strong spin–phonon coupling and the magnetic field induced change of FE polarization. In the context of charge redistribution without magnetic superlattice, the FE property is analyzed. Moreover, remarkable magnetic control of FE polarization and electric control of magnetization are obtained. The temporal evolution of both polarization and magnetization indicates the stable ME mutual control, suggesting potential applications of Cu3Mo2O9 as a promising multiferroic material. [ABSTRACT FROM AUTHOR]

α -MnTe is an antiferromagnetic semiconductor with above room temperature T N = 310 K, which is promising for spintronic applications. Recently, it was reported to be an altermagnet, containing bands with momentum-dependent spin splitting; time-resolved experimental probes of MnTe are, therefore, important both for understanding novel magnetic properties and potential device applications. We investigate ultrafast spin dynamics in epitaxial MnTe(001)/InP(111) thin films using pump-probe magneto-optical measurements in the Kerr configuration. At room temperature, we observe an oscillation mode at 55 GHz that does not appear at zero magnetic field. Combining field and polarization dependence, we identify this mode as a magnon, likely originating from inverse stimulated Raman scattering. Magnetic field-dependent oscillations persist up to at least 335 K, which could reflect coupling to known short-range magnetic order in MnTe above T N . Additionally, we observe two optical phonons at 3.6 and 4.2 THz, which broaden and redshift with increasing temperature. [ABSTRACT FROM AUTHOR]

An apparatus that accomplishes productive energy conversion by breaking conventional Kirchhoff's law is the nonreciprocal thermal emitter. Previous research universally focused on the nonreciprocal thermal emitter operated under transverse magnetic wave. The nonreciprocal thermal radiation proposed is operated under transverse electric (TE) wave, filling the gap in previous research. Meanwhile, the emitter, utilizing a photonic crystal (PC) heterostructure scheme composed of two one-dimensional PCs and an Al basement, accomplishes multi-channel nonreciprocal thermal radiation. With the external magnetic field of 3T, the emitter displays nonreciprocity behavior at bands of 15.933, 16.248, and 16.527 μm. Furthermore, under alternative sets of structural parameters, the structure can achieve four-port nonreciprocal radiation at bands of 16.437, 16.804, 17.139, and 17.478 μm. Both operating states indicate that the heterostructure under the magnetic field of 3 T exhibits nonreciprocal radiation performance for the TE wave. In addition, the exploration of the flat plate structure (IG)n(GI)mM shows that this scheme has multi-band nonreciprocity in TE wave. [ABSTRACT FROM AUTHOR]

Using purely electrical methods to manipulate magnetic property poses a significant obstacle in the development of advanced information technology. Multiferroic materials, distinguished by their magnetoelectric (ME) effect, offer a promising way to overcome this challenge by enabling the electric control of magnetic ordering or magnetization. Here, we have synthesized Cu3Mo2O9 single crystals and investigated the anisotropic ME effect within the quasi-one-dimensional spin system. The simultaneous occurrence of ferroelectric (FE) polarization and dielectric anomaly at the Néel temperature (TN) of ∼7.9 K suggests the presence of spin-driven FE property in Cu3Mo2O9. The phase transition temperatures undergo a shift toward lower values for H//c and remain constant for H//a and H//b, indicating anisotropic ME effect. The ME effect demonstrates nonlinear behavior as the magnetic field increases. Near a critical point (T = 7 K and μ0H = 5.6 T), a giant magnetodielectric coupling parameter reaching 374% is observed for H//c, which can be ascribed to the strong spin–phonon coupling and the magnetic field induced change of FE polarization. In the context of charge redistribution without magnetic superlattice, the FE property is analyzed. Moreover, remarkable magnetic control of FE polarization and electric control of magnetization are obtained. The temporal evolution of both polarization and magnetization indicates the stable ME mutual control, suggesting potential applications of Cu3Mo2O9 as a promising multiferroic material. [ABSTRACT FROM AUTHOR]

Target skyrmions (TSks) are topological spin textures where the out-of-plane component of the magnetization twists an integer number of k- π rotations. Based on a magnetic multilayer stack in the form of n × [CoFeB/MgO/Ta], engineered to host topological spin textures via dipole and DMI energies, we have stabilized 1 π , 2 π , and 3 π target skyrmions by tuning material properties and thermal-excitations close to room temperature. The nucleated textures, imaged via Kerr and Magnetic Force Microscopies, are stable at zero magnetic field and robust within a range of temperatures (tens of Kelvin) close to room temperature (RT = 292 K) and over long time scales (months). Under applied field (mT), the TSks collapse into the central skyrmion core, which resists against higher magnetic fields (≈ 2 × TSk annihilation field), as the core is topologically protected. Micromagnetic simulations support our experimental findings, showing no TSk nucleation at 0 K, but a ≈ 30 % probability at 300 K for the experimental sample parameters. Our work provides a simple method to tailor spin textures in continuous films, enabling free movement in 2D space and creating a platform transferable to technological applications where the dynamics of the topological textures can be exploited beyond geometrical confinements. [ABSTRACT FROM AUTHOR]

In this paper, we propose a method to determine the diagnostics of magnetic fields based on arrays of nano-thin-film probes that are manufactured by using magnetron sputtering-based fabrication and arranged in a two-dimensional (2D) topological design. Measurements of the magnetic field and its wave number based on the proposed method were validated in a linear cylindrical plasma device, the linear experimental advanced device. We manufactured nano-thin-film probes, each with a thickness of 500 nm, a diameter of 9 mm, and a shape similar to the Greek letter "omega" by depositing silver nanoparticles generated through magnetron sputtering to improve the accuracy of the fabrication as well as their time response. The 2D topological arrangement of the array of probes enabled the determination of the diagnostics of the magnetic field and its wave number at a high spatial resolution. Measurements of the amplitude of the magnetic field and its wavenumber obtained using the proposed method were in good agreement with the results of theoretical simulations in COMSOL, which verifies its high reliability and accuracy in obtaining low-pressure plasma diagnostics. In future work, we plan to apply our diagnostic method based on the array of thin-film probes to scenarios that require a high spatial resolution. [ABSTRACT FROM AUTHOR]

Magnetoelectric (ME) sensors have enormous potential for detecting weak magnetic fields because of their high sensitivity, low power consumption, compact size and, low cost. However, inevitable vibration interference limits their application in practical environments, especially in the case of mobile platform mounting. Here, we propose a differential ME sensor, consisting of PZT macro-fiber composites (MFCs) and Metglas laminates. The differential ME sensor has two output terminals with weak mutual mechanical coupling and works in longitudinal vibration mode. MFC cores are polarized in parallel mode to guarantee their consistency of electric characteristics and reversed bias field is provided by attached magnets. Experimental results show that the differential-mode response amplitudes have a gain of −17.6 dB for low-frequency vibration at 2 Hz and ∼6.2 dB for an applied magnetic field at 3 Hz, in comparison with the single-ended mode. In addition, our proposed ME sensor also has a low inherent equivalent magnetic noise of 18.3 pT/√Hz at 1 Hz. Finally, a target detection experiment in the presence of heavy lab noise and strong vibration interference is conducted and the improved detection performance of the proposed differential ME sensor is proved. [ABSTRACT FROM AUTHOR]

Flexible spintronic devices based on spin–orbit torque (SOT)-induced perpendicular magnetization switching (PMS) have attracted increasing attention due to their high storage intensity and good programming capability. However, to achieve deterministic PMS, an in-plane auxiliary magnetic field is required, which greatly limits its application. Here, we show that "robust" magnetic field-free SOT-driven PMS is realized in the oblique sputtered Pt/CoTb multilayers grown on a flexible polyimide substrate. "Robust" means the magnetic field-free SOT switching is highly repeatable and stable after 100 bending cycles under various bending conditions. Additionally, the fabricated flexible multilayers exhibit nearly linear and nonvolatile multistate plasticity as synapses and a nonlinear sigmoid activation function when acting as neurons. We construct a fully connected neural network for handwritten digit recognition, achieving an over 96.27% recognition rate. Our findings may spur further investigations on the SOT-based flexible spintronic devices for wearable artificial intelligence applications. [ABSTRACT FROM AUTHOR]

Two-dimensional van der Waals ferromagnets have garnered significant attention in spintronics due to their unique properties. Among them, CrTe2 flakes stand out because of their intrinsic in-plane magnetization and Curie temperature above room temperature. Despite these intriguing magnetic properties, the underlying mechanisms remain incompletely understood. In this paper, we meticulously investigate the magnetoresistance (MR) response of CrTe2 flakes to variations in magnetic field and temperature. Below 40 K, CrTe2 exhibits positive MR correlated with carrier density, including a distinctive linear non-saturating MR at 3 K. Above 40 K, the suppression of electron–magnon scattering leads to linear negative MR, which is a characteristic feature of ferromagnetic materials. As the temperature approaches 240 K, thermal excitations gradually increase, and scattering from fluctuating local moments begins to play a significant role, resulting in the nonlinear MR phenomenon. Magnetic anisotropy contributes to anisotropic MR across different current and magnetic field orientations. In low magnetic fields where the magnetic moment is unsaturated, we combined the localized magnetic moment and two-band models to explain the MR behavior, achieving good fitting results. These findings significantly enhance the understanding of CrTe2's ferromagnetic properties and magnetic transport behavior, laying a foundation for its future development and practical applications in spintronics. [ABSTRACT FROM AUTHOR]

The topological spin structures, such as skyrmions and merons, have increasingly been proposed as information carriers due to their topological characteristics and electrical maneuverability. Nevertheless, the difficulties in growing stable (especially stable under room temperature and zero magnetic fields) and large-scale topological lattices still restrict practical applications. This paper reviews the scientific efforts in facing this challenge comprehensively and simultaneously sums up the interaction between topological spin structures and current or light. The possibility of manipulating electron spin and photon chirality by the topological quasiparticles is emphatically discussed. This review paper aims to demonstrate scientific exploration for physical connotations on the interaction among topological quasiparticles and electrons and photons and to show the bridge built by researchers for the gap between scientific exploration and real-world application for topological spin structures. [ABSTRACT FROM AUTHOR]

Spin–orbit torque (SOT)-based perpendicularly magnetized memory devices with multistate memory have garnered significant interest due to their applicability in low-power in-memory analog computing. However, current methods are hindered by initialization problems, such as prolonged writing duration, and limitations, on the number of magnetic states. Consequently, a universal method for achieving multistate in perpendicular magnetic anisotropy (PMA)-based stacks remains elusive. Here, we propose a general experimental method for achieving multistate without any initialization step in SOT-driven magnetization switching by integrating an external out-of-plane magnetic field. Motivated by macrospin calculations coupled with micromagnetic simulations, which demonstrate the plausibility of magnetization state changes due to out-of-plane field integration, we experimentally verify multistate behavior in Pt/Co/Pt and W/Pt/Co/AlOx stacks. The occurrence of multistate behavior is attributed to intermediate domain states with Néel domain walls. We achieve repeatable 18 multistate configurations with a minimal reduction in retentivity through energy barrier measurements, paving the way for efficient analog computing. [ABSTRACT FROM AUTHOR]

Current-induced spin–orbit torque (SOT) has attracted much attention due to its potential applications in energy-efficient logic, memory, and artificial neuron devices. In this work, we report an enhanced SOT efficiency in perpendicularly magnetized Pt/Sm/Co/Ta heterostructures by inserting a light rare-earth Sm layer with large spin–orbit coupling. A series of Ta/Pt/Sm/Co/Ta samples with the Sm layer thickness (tSm) of 0, 0.6, 1.2, and 1.6 nm were prepared using direct-current magnetron sputtering. Perpendicular magnetic anisotropy, SOT efficiency, and current-driven magnetization reversal were characterized using electrical transport methods based on the anomalous Hall effect. The experimental results indicated that the switching field and magnetic anisotropic field decreased monotonically with an increase in tSm, while the damping-like effective field and effective spin Hall angle ( θ S H eff ) gradually increased. It demonstrates that interface modification with a Sm layer can improve the SOT efficiency and reduce the pinning potential barrier. Owing to the enhanced SOT and reduced pinning field, the critical switching current density (Jc) exhibits a steady decline when increasing tSm. In particular, the lowest Jc of approximately 7.83 × 106 A/cm2 was obtained when tSm was 1.6 nm. X-ray photoelectron spectroscopy revealed that electron transfer occurred between the Co, Pt, and Sm layers, which may be primarily responsible for the enhanced SOT by interface alloying to effectively strengthen the spin Hall effect of Sm and/or Pt. Our results provide a strategy for improving SOT efficiency and reducing Jc by interface alloying in SOT-based spintronic devices. [ABSTRACT FROM AUTHOR]

Topological spin structures have recently received tremendous attention in condensed matter physics and information science. In addition to the frequently studied skyrmion, skyrmioniums that exhibit a zero topological charge are also promising for spintronics memory carriers. Here, through integrating an interfacial asymmetric Ta/CoFeB/MgO multilayer device with an on-chip conducting wire that induces Oersted fields and Joule heating, we show experimentally the creation and annihilation of magnetic Néel-type skyrmioniums at room temperature, without applying external magnetic fields. In particular, we observe two distinct annihilation dynamics of the skyrmionium by a polar magneto-optical Kerr microscope. Under the direction of Oersted fields that are parallel to the core direction of the skyrmionium, the skyrmionium shrinks inward to form a skyrmion. Under the antiparallel configuration, skyrmionium expands outward to form a stripe domain. By performing micromagnetic simulations, we reveal the Néel-type skyrmionium formation and annihilation dynamics as well as the corresponding energy changes among different magnetic states. Our findings could be important for understanding the formation and annihilation dynamics of skyrmioniums, which also provide an on-chip non-electrical-contact manipulating method of skyrmioniums. [ABSTRACT FROM AUTHOR]

This study explores the impact of different magnetic driving field waveforms on nanoparticle heating in magnetic hyperthermia. Our research, which shifts the usual focus from individual nanoparticle properties to interacting particle clusters, evidences that square waves induce more uniform and greater heating than sinusoidal waves. The sequential switching observed with sinusoidal waves, which additionally strongly depends on the alignment of the particle cluster with respect to the direction of the field, leads to less uniform heating within and among different clusters. In contrast, a square waveform leads to simultaneous particle switching, thereby homogenizing the heat and potentially mitigating hazardous hot spots. These findings reaffirm the potential advantages for magnetic hyperthermia treatments using non-harmonic field waveforms, offering more uniform heating and the possibility of reducing the applied field exposure. [ABSTRACT FROM AUTHOR]

Magnetic two-dimensional (2D) materials have garnered significant attention due to their unique electronic, magnetic, and optical properties and their potential applications in next-generation electronic and optoelectronic devices. However, the magneto-optical effects of oligolayer antiferromagnetic materials remain inadequately understood. Here, we investigate the magnetic properties of few-layer nickel phosphorus trisulfide (NiPS3) and its twisted heterostructures, emphasizing the observation of optical phenomena at low temperatures (1.65 K). By stacking few-layer NiPS3 to fabricate twisted homostructures, we probe their magnetic characteristics using photoluminescence (PL) spectroscopy. Our results reveal that sharp exciton peaks emerge at low temperatures and that the spin chain orientation in oligolayer NiPS3 can be discerned through the polarization dependence of exciton PL intensity. Notably, fewer-layered NiPS3 exhibits a significant magneto-optical effect under an applied magnetic field, allowing the modulation of the polarization angle of its exciton PL spectrum. Additionally, the polarization-dependent Raman spectrum of NiPS3 shows substantial changes under the influence of a magnetic field. These findings underscore the potential of few-layer NiPS3 for future magneto-optical device applications. [ABSTRACT FROM AUTHOR]

Magnetic field effects have received widespread attention due to their ability to enhance the process of water splitting at multiple scales. However, a systematic and comprehensive understanding of the source of the magnetic effect and the magnetic modulation of magnetic catalysts is lacking. This perspective focuses on recent advancements in harnessing external magnetic field to improve electrocatalytic water splitting and suggests future directions. First, the mechanism of several magnetic effects and their effects on water splitting are elaborated in detail, including the magnetohydrodynamic effect, magnetothermal effect, spin polarization effect, and magnetoresistance effect. Then, the classification and construction strategies of magnetic effect catalysts are summarized, primarily divided into single metal/alloy catalysts, metal oxide-based catalysts, and other magnetic catalysts. Finally, the challenges and potential perspective of magnetic field-enhanced water splitting are discussed, including mechanism study, in situ characterization, and multi-field synergy effects. [ABSTRACT FROM AUTHOR]

Planaria serve as an intriguing model system wherein the effects of electric and magnetic fields on various biochemical pathways during cell morphogenesis can be studied. Recent experimental observations have demonstrated the non-trivial modulation of reactive oxygen species (ROS) levels by a weak magnetic field (WMF) during planaria regeneration. However, the underlying biophysical mechanism behind this remains elusive. In this work, we investigate the role of the radical pair mechanism (RPM) and attempt to explain the experimental results of the effect of WMFs on ROS modulation during planaria regeneration. We also propose that instead of the flavin adenine dinucleotide-superoxide radical pair (FAD H • − O 2 • − ), a non-superoxide-based flavin adenine dinucleotide-tryptophan radical pair (F A D • − − Trp H • + ) might be a more suitable radical pair (RP) candidate for the observed ROS modulation. We also investigate the role of chirality-induced spin selectivity on ROS levels by including it in the framework of the RPM. We conclude that the singlet initiated F A D • − − Trp H • + is a more realistic choice of RP, and hence, superoxide formation might happen later and not during the RP spin dynamics. [ABSTRACT FROM AUTHOR]

We studied the interfacial spin Hall magnetotransport in the Tb3Fe5O12 (TbIG)/Pt system across a non-magnetic [Y3Al5O12 (YAG) and Gd3Ga5O12 (GGG)] spacer with garnet structure. TbIG (30 nm)/spacer samples were grown on single-crystal (GGG) (111) substrates by pulsed laser deposition before 5 nm of Pt was sputtered on the samples and patterned into Hall bars. The YAG spacer thickness (tYAG) dependences of anomalous Hall effect resistance (RAHE) indicated no significant change on the magnetization compensation temperature of TbIG. Hysteretic RAHE loops were observed at low magnetic fields, but with reducing magnitude as tYAG thickness increases. A crossover of the RAHE sign was observed at temperatures below the compensation temperature, which decreased sharply from 135 to 34 K as tYAG increased from 0 to 1 nm. We attributed this to the strong dependence of the magnetic proximity effect toward the YAG insertion in the TbIG/Pt interface. Replacement of the YAG spacer with GGG showed significant impact on the RAHE behavior. No obvious RAHE-H loops were observed in the TbIG/Pt sample inserted with 0.5 nm GGG spacer, which could be linked to the strong magnetic contribution of the Gd ions. This work highlights the tunability of interfacial transport behavior in iron garnet/heavy metal systems through ultrathin spacers, providing guidance for the interfacial design of spintronic devices. [ABSTRACT FROM AUTHOR]

We investigated the photo-thermoelectric response of Landau-quantized graphene in an infrared optical cavity structure. High-quality graphene/h-BN heterostructure was fabricated on a TiO2/Au optical cavity. We observed a large enhancement of the photo-thermoelectric voltage when the energy of the inter-Landau-level optical absorption, so-called cyclotron resonance, was coincident with that of the cavity mode. This is due to cavity-enhanced cyclotron resonance absorption of mid-infrared light. A maximum photovoltage responsivity of ∼107 V/W was obtained at a wavelength of 9.27 μm under a magnetic field as low as ∼1 Tesla. The obtained responsivity was significantly higher than that of conventional graphene devices. Our results provide an efficient photo-thermoelectric conversion scheme that utilizes Landau-quantized graphene and an optical cavity. [ABSTRACT FROM AUTHOR]

Skyrmions are intriguing quasiparticles in the field of condensed matter due to their unique physics and promising applications in spintronic devices. However, despite abundant studies on skyrmions with a topological charge of Q = 1, there have been only few on those with higher Q (≥ 2) due to their intrinsic instability in Dzyaloshinskii–Moriya interaction (DMI) systems. In this work, applying the frustrated J 1 − J 2 Heisenberg spin model, we investigate the stability of high-Q skyrmions and the manipulation of their diameters in a hexagonal close-packed lattice through atomistic simulations and first-principles calculations. First, three spin textures, called spiral, skyrmion, and ferromagnetic, are identified by varying ( J 1 , J 2 ), and it is shown that skyrmions with higher Q can occupy a wider range of ( J 1 , J 2 ) values. The diameter of the skyrmions can then be finely tuned using the frustration strength (| J 2 / J 1 |), the single-ion anisotropy (K), and an external magnetic field (B). As B increases, the high-Q skyrmions split into skyrmions with smaller Q and can be annihilated by a larger B. Furthermore, we find that the CoCl2 monolayer satisfies the criteria for a frustrated J 1 − J 2 magnet, and its magnetic behaviors align with the aforementioned conclusions. In addition, high-Q skyrmions are identified in the CoCl2 monolayer, and the corresponding energy barriers for skyrmion collapse are investigated. Our findings pave the way for prospective spintronic applications based on high-Q and nanoscale skyrmionic textures. [ABSTRACT FROM AUTHOR]

Magneto-oscillatory devices have been recently developed as very potent wireless miniature position trackers and sensors with an exceptional accuracy and sensing distance for surgical and robotic applications. However, it is still unclear to which extend a mechanically resonating sub-millimeter magnet interacts with external magnetic fields or gradients, which induce frequency shifts of sub-mHz to several Hz and, therefore, affect the sensing accuracy. Here, we investigate this effect experimentally on a cantilever-based magneto-oscillatory wireless sensor (MOWS) and build an analytical model concerning magnetic and mechanical interactions. The millimeter-scale MOWS is capable to detect magnetic fields with sub-µT resolution to at least ±5 mT and simultaneously detects magnetic field gradients with a resolution of 65 µT/m to at least ±50 mT/m. The magnetic field sensitivity allows direct calculation of mechanical device properties, and by rotation, individual contributions of the magnetic field and gradient can be analyzed. The derived model is general and can be applied to other magneto-oscillatory systems interacting with magnetic environments. [ABSTRACT FROM AUTHOR]

The precise quantitative analysis of magnetic nanoparticles is crucial for their applications in biomedicine. This work presents the research and development of a measurement system based on a compact spin–exchange–relaxation–free atomic magnetometer, capable of rapidly detecting the concentration and flow rate of magnetic nanoparticles in solution. By designing spatial magnetic field gradients, the system creates a quasi-zero field environment for the magnetometer while providing a large excitation magnetic field for the magnetic nanoparticles. The droplet method facilitates the preparation of minimal amounts of nanoparticle samples. With a sensitivity of 25 f T / H z , the magnetometer system can measure concentrations as low as 0.1 mg/ml in a 2 μl sample, corresponding to a nanoparticle mass of 200 ng, with a measurement error of less than 11.8 ng. This method's strengths lie in its minimal sample consumption and single-measurement low mistake, rendering it highly suitable for rapid detection or applications involving small-volume samples, particularly in immunoassay reagents. In addition to measuring particle concentration, this system can also monitor the flow rate of nanoparticles during the measurement process, providing a noninvasive means for dynamic monitoring. [ABSTRACT FROM AUTHOR]

Magnetoelectric response in thin films is highly desirable for high-throughput and high-density microelectronic applications, like magnetic sensors. To sensitively detect the direction of magnetic field, the anisotropic magnetoelectric effect is required. Here, we artificially design an anisotropic magnetoelectric response in Sr2IrO4/SrTiO3 superlattices, where a strong (negligible) magnetoelectric response for magnetic fields along the z-direction (xy-plane) of Sr2IrO4/SrTiO3 interface was observed. A combination of perturbative calculations with numerical results and density functional theory calculations reveals that only the effective z-component Zeeman field within the Sr2IrO4 layers can change the electron occupation of the neighboring SrTiO3 layers, which is proportional to the polarization. Via controlling the periodicity of the superlattices, we can further control the anisotropy of magnetoelectric responses. This atomic-scale design of 3d/5d superlattices paves an alternative way toward controllable magnetoelectric effects with thin film integrations. [ABSTRACT FROM AUTHOR]

The interfacial Dzyaloshinskii–Moriya interaction (DMI) acting as an essential source to stabilize spin textures in ferromagnetic ultrathin films has revealed its significant role in spin–orbit torque (SOT)-driven magnetic switching. Based on a convincing homochiral Néel domain wall model, the in-plane (IP) magnetic field associated with the DMI effect has been confirmed as an essential prerequisite for deterministic SOT-driven switching. Although the presence of the IP field is required, the impact of IP field magnitude combined with the DMI effect on SOT-driven switching in different heavy metals (HMs) has never been considered together. In this research, SOT-induced switching under various IP fields in Pt, W, or Ta/CoFeB/MgO systems has been studied. The results show that the critical threshold current IC is almost independent of the IP field in the Pt-based structure; however, it significantly decreases with an increase in the IP field in the W- and Ta-based systems. Combining the derived DMI field and the magnetic domain nucleation, it is concluded that the significant difference in DMI fields and the domains' nucleating positions are the main reasons for the above phenomenon. Exploiting the distinct dependent properties of IC on the IP field, a six resistance state multilevel storage and five programmable spin logic gates are proposed and realized. This study provides insight into the special ability of the SOT effect modulated by the DMI, and also expands an effective way to construct spin-based devices based on this unique spintronic effect. [ABSTRACT FROM AUTHOR]

Ferromagnetic shape memory alloys attracted increasing interest as multicaloric materials for solid state refrigeration. The most effective field coupling is achieved through the combination of the magnetic and mechanical induction of thermoelastic martensitic transformation. In the present work, we present an experimental investigation on NiMnGaCu polycrystalline cast alloy, by means of an experimental setup for compression tests in isothermal conditions under a longitudinal magnetic field. The setup has been ad hoc designed and developed specifically for this purpose. In this way, we can measure the elastocaloric and magnetocaloric effect at the same time. Moreover, the evolution of the entropy changes ΔS and the functional caloric parameters vs the magnetic field is evaluated. The application of magnetic field seems to act like a supplementary mechanical longitudinal stress. These preliminary results are fundamental to achieve a comprehensive understanding and modeling of coupled multicaloric phenomena. [ABSTRACT FROM AUTHOR]

We observe concurrent precessional and partial orbital motion of highly birefringent liquid crystal (LC) particles trapped in a spherically aberrated optical trap, which is built employing a tilted refractive index stratified medium. For input circularly polarized light, the breaking of azimuthal symmetry induced by the tilt leads to an asymmetric intensity distribution in the radial direction near the trap focal plane, which—in combination with the spin–orbit conversion effects for input circularly polarized light—results in nonuniform canonical and spin momentum densities in those regions. In addition, while the canonical momentum remains always oriented toward the axial direction, the spin momentum reverses direction along spatial loops in the radial direction. As a consequence, the total momentum precesses around the canonical momentum vector along elliptical spatial loops—akin to a Larmor-like precession of magnetic moment (total momentum in our case) around a magnetic field (canonical momentum). We probe this precession experimentally using the single trapped LC particles—with the direction of precession and orbital motion determined by the helicity of the input light, with the precession frequency varying linearly with the laser power. Our experimental results are validated by numerical simulations of the system where we employ the Debye–Wolf theory for tight focusing in the presence of a tilted stratified media. [ABSTRACT FROM AUTHOR]

In the last decade, quantum resistance metrology has benefited from the application of graphene as the base material for the fabrication of quantum Hall (QH) resistance standards since it allows for the realization of the resistance unit ohm in the revised International System of Units under relaxed experimental conditions. Here, we present a detailed magnetotransport investigation of p-type epitaxial graphene, which was doped by the molecular acceptor F4-TCNQ. High-accuracy measurements of the QH resistance show an excellent quantization and a reproduction of the nominal value, the half of the von Klitzing constant RK/2, within 2 nΩ/Ω. It underlines the universality of the QH effect and shows that p-type epitaxial graphene can also serve as the basis for future resistance standards for operation at relaxed experimental conditions. For the p-type devices, the onset of the QH plateau is observed at about 1 T higher magnetic fields, which can be attributed to an additional disorder or a non-symmetric charge transfer mechanism in the QH regime. [ABSTRACT FROM AUTHOR]

Nonreciprocity has become a research hotspot in the field of thermal radiation. Nonetheless, the majority of current nonreciprocal thermal radiation is confined to TM polarization. This paper introduces a two-dimensional nanograting structure exhibiting strong dual-polarization nonreciprocal thermal radiation. The grating is composed of a GaAs-based periodic nanoarray, a magneto-optic medium layer (InAs), and a metallic reflective layer (Al). The impact of nonreciprocity under different polarizations was investigated using rigorous coupled-wave analysis. Additionally, the magnetic field energy distribution was studied, and an explanation for the observed phenomenon of the device's nonreciprocal thermal radiation was given for both TE and TM polarizations. The present study is expected to contribute insights for the study of nonreciprocal thermal radiation. [ABSTRACT FROM AUTHOR]

We explored the coupling between magnetic and magneto-transport properties in MnBi2Te4 crystals with Fermi energy EF ranging from 10 to 100 meV in the conduction band. Electrical, magnetic, and magneto-transport measurements reveal distinct behaviors depending on EF. At lower EF values (10 meV), MnBi2Te4 exhibits degenerate-semiconductor-like electrical transport and ferrimagnetism, with weak coupling between magneto-resistance and ferrimagnetism. In contrast, MnBi2Te4 displays metallic transport and antiferromagnetism (AFM) at higher Fermi energies, with magneto-resistance strongly coupled to antiferromagnetism and canted antiferromagnetism under a large external magnetic field. Remarkably, Hall measurements demonstrate a pronounced anomalous Hall resistivity (AHR) when the EF of MnBi2Te4 is 10 meV, larger than that reported for other bulk MnBi2Te4 crystals in the literature. Significant AHR is attributed to the Berry-phase effect in electronic-band structure based on first-principles calculation. The evolution of magnetic and magneto-transport properties in EF shifted MnBi2Te4 can be semi-quantitatively explained by the Ruderman–Kittel–Kasuya–Yosida interaction between neighboring MnTe layers. Our work suggests that the strongly Fermi-energy-sensitive magneto-transport properties observed in MnBi2Te4 may be useful in developing magnetic sensors/detectors. [ABSTRACT FROM AUTHOR]

Controllable coupling between the odd and even fundamental modes of an asymmetric half-wavelength superconducting coplanar waveguide resonator is demonstrated. The resonant frequency of the even mode Ω e could be tuned by an external magnetic field, while the resonant frequency of the odd mode Ω o is field independent. To realize the tunability of Ω e , the central conductor of the NbN-based resonator was galvanically coupled to an array of Al-based rf-SQUIDs (radio frequency superconducting quantum interferometer device). These rf-SQUIDs are placed in only one resonator gap, ensuring its strong asymmetry. By adjusting the appropriate external magnetic flux Φ , equal frequencies of both modes were obtained. At this resonant point Ω o (Φ) = Ω e (Φ) an avoided level crossing of the eigenfrequencies was observed, demonstrating the coupling between the odd and even fundamental modes. [ABSTRACT FROM AUTHOR]

The study aimed to investigate the underlying physics limiting the temperature stability and performance of non-surface passivated Al0.34Ga0.66N/GaN Hall effect sensors, including contacts, under atmospheric conditions. The results obtained from analyzing the microstructural evolution in the Al0.34Ga0.66N/GaN Hall sensor heterostructure were found to correlate with the electrical performance of the Hall effect sensor. High-resolution x-ray photoelectron spectroscopy studies revealed the signature of surface oxidation in the GaN cap layer, as well as a slight out-diffusion of "Al" from the AlGaN barrier layer. To prevent the formation of a bumpy surface morphology at the Ohmic contact, we investigated the impact of "Pt" top Ohmic contacts. The application of a top "Pt" contact stack resulted in a smooth Ohmic contact surface and provided evidence that the bumpy surface morphology in Au-based Ohmic contacts is due to the formation of an Al-Au viscous alloy during rapid thermal annealing. In the early stages of thermal aging, the small drop in contact resistivity stabilized with subsequent thermal aging past the initial 550 h at 200 °C. The outcome is that the Al0.34Ga0.66N/GaN Hall effect sensors, even without surface passivation, exhibited a stable response to applied magnetic fields with no sign of significant degradation after 2800 h of thermal aging at 200 °C under atmospheric conditions. This observed stability in the Hall sensor without surface passivation can be attributed to a self-imposed surface oxidation of the cap layer during the early stages of aging, which serves as a protective layer for the device during subsequent extended periods of thermal aging at 200 °C. [ABSTRACT FROM AUTHOR]

Searching the optimal doping compositions of the Y-type hexaferrite Ba2Mg2Fe12O22 remains a long-standing challenge for enhanced non-collinear magnetic transition temperature (TNC). Instead of the conventional trial-and-error approach, the composition-property descriptor is established via a data driven machine learning method named sure independence screening and sparsifying operator. Based on the chosen efficient and physically interpretable descriptor, a series of Y-type hexaferrite compositions are predicted to hold high TNC, among which the BaSrMg0.28Co1.72Fe10Al2O22 is then experimentally validated. Test results indicate that, under appropriate external magnetic field conditions, the TNC of this composition reaches up to 568 K, and its magnetic transition temperature is also elevated to 735 K. This work offers a machine learning-based route to develop room temperature single phase multiferroics for device applications. [ABSTRACT FROM AUTHOR]

Flaky structures can effectively enhance the microwave absorbing properties of metallic magnetic particles, but the interaction between the electromagnetic waves and particles in different directions is not well understood. Here, the oriented FeSiAl/paraffin composites were prepared under a rotational magnetic field and made into co-axial rings for electromagnetic measurements. The FeSiAl flakes in the rings are oriented along different angles with respect to the electric and magnetic fields of the microwave. The effects of the angles on the electric and magnetic properties as well as the microwave absorbing properties of the composite are investigated. It is found that the electric and magnetic properties can be modified independently by adjusting the angles between the flakes and the electric field and between the flakes and the magnetic field, respectively. The underlying mechanisms can be understood using electromagnetic and micromagnetic simulations. The anisotropic permittivity originates from the induced electric field of the flaky particles, while the anisotropic permeability results from the effect of the demagnetization field. An optimal orientation structure can reduce the permittivity by suppressing the induced electric field while maintaining high permeability by reducing the demagnetization energy in the magnetization process, which is beneficial to the impedance matching of the composite. Thus, the orientation structure is extremely efficient in regulating the microwave absorption performance of the flaky particles. This work proposed a general strategy for microwave absorbers to modulate microwave absorption performances between high-frequency and low-frequency by simply operating the orientation structures of the flaky particles. [ABSTRACT FROM AUTHOR]

Nonreciprocal transport effects can occur in the normal state of conductors and in superconductors when both inversion and time-reversal symmetry are broken. Here, we consider systems where magnetochiral anisotropy of the energy spectrum due to an externally applied magnetic field results in a rectification effect in the normal state and a superconducting (SC) diode effect when the system is proximitized by a superconductor. Focusing on nanowire systems, we obtain analytic expressions for both normal state rectification and SC diode effects that reveal the commonalities—as well as differences—between these two phenomena. Furthermore, we consider the nanowire brought into an (almost) helical state in the normal phase or a topological SC phase when proximitized. In both cases, this reveals that the topology of the system considerably modifies its nonreciprocal transport properties. Our results provide insights into how to determine the origin of nonreciprocal effects and further evince the strong connection of nonreciprocal transport with the topological properties of a system. [ABSTRACT FROM AUTHOR]

Anomalous critical current enhancement was observed with increasing magnetic field in Josephson junctions based on Ge–Si core-shell nanowires. Despite the predicted topological properties of these nanowires, which could potentially lead to non-trivial superconducting order parameter symmetries, our investigation unveils a more generalized, non-topological explanation for the observed critical current enhancement in these devices. Our findings suggest that the enhancement arises from a thermalization process induced by the magnetic field, wherein in-gap quasiparticles are generated. These quasiparticles play a crucial role in enhancing the cooling of the device, thereby lowering the effective temperature and resulting in an increased critical current. Furthermore, we elucidate how this thermalization effect varies with device geometry and measurement configuration. [ABSTRACT FROM AUTHOR]

Thin Bi films, especially noncentrosymmetric α-phase Bi films (α-Bi), have attracted considerable attention in recent years due to their intriguing physical properties such as ferroelectricity, nonlinear optical response, and coherent spin transport. However, the current experimental preparation of α-Bi films still presents substantial challenges, resulting in only isolated α-Bi islands being achieved. In this study, α-Bi/SrTiO3 (α-Bi/STO) was synthesized from a Bi2O2Se/STO (BOS/STO) heterostructure by depositing a Eu layer and reducing a BOS film. The so-formed α-Bi/STO interface features metallic conductivity with electron mobility of 7.7 × 104 cm2/V s and ultralow resistivity of 1 nΩ cm at 2 K, as well as high residual resistance ratios R300 K/R2 K up to 2353. Furthermore, we observed a complex weak antilocalization–weak localization–weak antilocalization crossover with increasing magnetic field at temperatures below 10 K. Our work presents the synthesis of α-Bi films, which could potentially serve as a valuable platform for experimental validation of diverse theoretical predictions associated with α-Bi heterostructures. Furthermore, this special synthesis method provides valuable insights into the preparation of other metastable films. [ABSTRACT FROM AUTHOR]

Thin Bi films, especially noncentrosymmetric α-phase Bi films (α-Bi), have attracted considerable attention in recent years due to their intriguing physical properties such as ferroelectricity, nonlinear optical response, and coherent spin transport. However, the current experimental preparation of α-Bi films still presents substantial challenges, resulting in only isolated α-Bi islands being achieved. In this study, α-Bi/SrTiO3 (α-Bi/STO) was synthesized from a Bi2O2Se/STO (BOS/STO) heterostructure by depositing a Eu layer and reducing a BOS film. The so-formed α-Bi/STO interface features metallic conductivity with electron mobility of 7.7 × 104 cm2/V s and ultralow resistivity of 1 nΩ cm at 2 K, as well as high residual resistance ratios R300 K/R2 K up to 2353. Furthermore, we observed a complex weak antilocalization–weak localization–weak antilocalization crossover with increasing magnetic field at temperatures below 10 K. Our work presents the synthesis of α-Bi films, which could potentially serve as a valuable platform for experimental validation of diverse theoretical predictions associated with α-Bi heterostructures. Furthermore, this special synthesis method provides valuable insights into the preparation of other metastable films. [ABSTRACT FROM AUTHOR]

Multiferroic materials have important research significance in the fields of magnetic random-access memory, ferroelectric random-access memory, resistive random-access memory, and neuromorphic computing devices due to their excellent and diverse physical properties. In this work, a solution of Bi2FeMnO6 was prepared using a solution-based method, and an Au/Bi2FeMnO6/TiO2 heterostructure device was fabricated on a Si substrate. X-ray diffraction and transmission electron microscopy data indicate that the Bi2FeMnO6 films have hexagonal R3c symmetry structures. The Bi2FeMnO6 film exhibits ferroelectricity with a fine remanent polarization. In addition, the Bi2FeMnO6-based devices have excellent switching ratios of 6.37 × 105. A larger switching ratio can provide a multi-resistance state for the device, which is beneficial for the simulation of synapses. Hence, it effectively emulates excitatory postsynaptic currents, paired-pulse facilitation, and long-term plasticity of synapses and achieves recognition accuracy of 95% in neuromorphic computing. We report a promising material for the development of various nonvolatile memories and neuromorphic synaptic devices. [ABSTRACT FROM AUTHOR]