Sluggish dynamics of photogenerated charge carriers greatly hinder photocatalytic activity. This limitation was overcome by synergistically enhanced macroscopic spontaneous polarization with precisely controlled ferroelectric domain orientation. This was accomplished through a rational sequential strategy comprising an initial in-situ reduction process followed by corona polarization for bismuth titanate (Bi4Ti3O12) nanosheets. In-situ reduction induced more positive and negative charge centers within Bi4Ti3O12 nanosheets (Bi/Bi4Ti3O12), as evidenced by electron localization function (ELF). Then corona polarization aligned polarization vector orientation of Bi/Bi4Ti3O12 nanosheets (Bi/Bi4Ti3O12-P), as demonstrated by piezoelectric force microscopy (PFM). Thereby, the polarization strength of Bi4Ti3O12 was enhanced through the sequential combination of these methods gradually. A significant improvement in piezoelectric coefficient (d33) has been achieved in Bi/ Bi4Ti3O12-P nanosheets (0.19 mV/V), representing a 3.17-fold increase over that of Bi4Ti3O12 (0.06 mV/V) samples. Kelvin probe force microscopy (KPFM) confirmed that this approach effectively promoted the migration of photogenerated electrons to the catalyst surface. The normalized surface potential difference of the highly polarized Bi/Bi4Ti3O12-P nanosheets under illumination was 3.04 times higher than that of pristine Bi4Ti3O12. Consequently, the Bi/Bi4Ti3O12-P nanosheets exhibited a high carbon monoxide (CO) yield rate of 16.80 mu mol/g/ h under irradiation, nearly 4.67 times higher than that of Bi4Ti3O12. This work demonstrates an effective approach for designing high-performance ferroelectric photocatalysts through the precise manipulation of positive and negative charge centers and polarization vector orientations.

Oxidation engineering provides a route to control orbital degrees of freedom, yet its role in spin-to-orbital conversion remains largely unexplored. Here, we report an efficient spin-to-orbital conversion mechanism driven by interfacial oxidation at heavy-metal interfaces. In W/Co/SiO2 heterostructures, terahertz emission exhibits a time delay that scales linearly with the W thickness, identifying orbital-current transport as the dominant origin. The emission amplitude is approximately three times larger than that of Co/Pt bilayers, indicating highly efficient conversion from spin to orbital angular momentum. Systematic variation of Co thickness, stoichiometry, and interface configuration reveals that the effect originates from oxidation of the W layer at the W/Co interface, which modulates the interfacial orbital texture. We further show that this mechanism is generic across different heavy metals and scales with their spin-orbit coupling strength. These results establish oxidation as an effective handle to engineer spin-to-orbital conversion and provide a general route toward orbitronic terahertz emitters.

Ba3Co2Fe24O41 (Co2Z) is a hexagonal ferrite material in which achieving synergistic control of magnetic and dielectric properties in the MHz-GHz range remains a key challenge. This study explores the modulation of these properties in Co2Z through doping with highly polarizable Bi3 + ions. A combination of experimental analysis and first-principles calculations was used to investigate the effects of Bi3+ doping on phase evolution, crystal structure, magnetic behavior, and dielectric response. The results show that Bi3+ incorporation effectively lowers the synthesis temperature of the Z phase to approximately 1150 degrees C and enhances both the magnetic permeability and permittivity of Co2Z. At a doping level of x = 0.3, Co2Z exhibits optimal impedance matching and a notable miniaturization factor for antenna substrates operating in the MHz-GHz range. These findings provide theoretical insights and practical guidance for the design of high-performance Co2Z-based materials for advanced antenna applications.

A single-step cold sintering process (CSP) was developed to achieve low-temperature densification of Co(2)Z-Li2MoO4 (LMO) composite ceramics for radio frequency applications. Both phases retained their crystal structures during CSP, LMO precipitated into the interplatelet gaps, promoting particle rearrangement and filling original porosity. Consequently, relative density increased from 76 % for pure Co(2)Z to over 94 % in the composites. Although LMO is nonmagnetic, the substantial increase in densification leads to pronounced improvements in magnetodielectric properties. Low LMO loadings improved permeability, while higher loadings increased permittivity and reduced dielectric loss by an order of magnitude. This work demonstrates that cold sintering with a second phase enables low-temperature densification of Co(2)Z-based ceramics with available magnetodielectric properties for antenna substrates.

Abstract Terahertz emission based on orbital electronics offers exciting prospects for regulating terahertz emission and improving its efficiency. However, the transport characteristics of orbital current in many materials remain largely unexplored. In our manuscript, we use terahertz time-domain spectroscopy to investigate orbital angular momentum transport as well as orbital-to-charge conversion in Ni/Ta bilayers. By changing the thickness of the Ta layer, we quantitatively analyze the terahertz amplitude and time delay to study the orbital angular momentum transport in Ta and its conversion to ultrafast charge current via the orbital Hall effect. We determine the ballistic transport length (~ 20 nm) and ballistic transport velocity (~ 0.21 nm / fs) of the orbital angular momentum transport in the nonmagnetic Ta. Our results provide direct experimental evidence for thickness-dependent orbital charge conversion and transport in heavy metal Ta, offering new insights into the manipulation of orbital current in ultrafast spin-orbit electronics.

Here, a nearly twofold increase in spin-to-charge conversion efficiency within YIG/heavy-metal heterostructures, achieved through Ar+ ion bombardment and chemical treatment, is demonstrated. By inducing a gradient distribution of Fe vacancies confined to a 2-nm skin depth of single-crystal YIG films, a strongly inversion-broken interface amplifying the inverse Rashba-Edelstein effect (IREE) is established. Structural characterization via STEM-EDS/TOF-SIMS confirms the depth-resolved Fe vacancy gradient, while ferromagnetic resonance and inverse spin Hall effect measurements revealed a 170% enhancement in the spin-to-charge conversion efficiency. Control experiments with Cu interlayers and Au cappings exclude contributions from bulk spin Hall mechanisms and magnetic proximity effects, thereby directly linking the enhancement to the interfacial IREE. This defect-engineering strategy offers a scalable pathway for high-efficiency spintronic devices compatible with YIG/heavy-metal systems.

Orbitronics is an emerging field in which orbital currents are used to develop high-efficiency electronic information devices. Orbital currents have a wider material range and longer transmission distance than spin currents. However, the efficient utilization of orbital currents remains challenging. In this paper, the study reports a giant effective orbital Hall angle in a Ti/Pt metallic heterostructure for efficient magnetization switching. The effective orbital Hall angle of Ti/Pt/Permalloy (Ni81Fe19) reaches 2.4 ± 0.5, a 14-fold increase relative to that of Ti/Ni. By constructing an interface orbital current transmission model, the study found that the effective orbital Hall angle is closely related to the interface spin-orbit coupling. In addition, research obtained a critical magnetization switching current density of Ti/Pt as low as 5.7 × 105 A/cm2, which is comparable to that of topological insulators. Based on this metallic heterostructure, the study demonstrates high-efficiency and low-dissipation Boolean logic operation. These metallic heterostructures, which combine a large effective orbital Hall angle and ease of integration with semiconductors, have significant implications for large-scale orbitronic device applications.

With microelectronic devices moving toward greater integration, smaller size and higher frequency, embedding high-performance antennas in packaging has become a key challenge. Co(2)Z ferrite offers high permeability and permittivity in the gigahertz band, making it ideal for low-impedance antenna substrates. Yet its conventional fabrication requires temperatures above 1000 degrees C, which consumes much energy and prevents use on low-melting-point substrates. The cold sintering process uses a small amount of liquid medium and high pressure to densify powders below 300 degrees C, offering a route to preserve Co(2)Z's functional properties while enabling low-temperature integration. In this work we evaluate the effects of three solvent systems on cold sintering of Co(2)Z ferrite, focusing on densification, microstructure and high frequency magnetic and dielectric properties. Pure water hardly densifies Co(2)Z, while acetic acid and a NaK hydroxide mixture yield relative densities of 83% and 85%, respectively. The NaK treated sample shows a slight reduction in saturation magnetization to 48 emu/g from the nonmagnetic alkali phase, and the acetic acid sample drops to 45 emu/g due to partial dissolution. In the microwave band the NaK hydroxide cold sintered Co(2)Z exhibits permeability and permittivity values between 5 and 6 and higher loss than the conventionally sintered ceramic. These findings highlight the need to balance the low temperature advantage of cold sintering Co(2)Z ceramics with its impact on functional performance.

Understanding the transport dynamics of orbital angular momentum in solids is crucial for the development of next-generation spintronic devices. Here, we provide experimental evidence of a ballistic-to-diffusive transition of orbital current transport in the ferromagnetic metal Ni. By systematically varying the Ni thickness and probing the resulting terahertz emission, we observe abrupt changes in both the delay and amplitude of the extracted ultrafast charge current. These changes are indicative of a transition from ballistic to diffusive orbital transport within the Ni layer. A numerical model is constructed to explain the observed delay, yielding a critical length of ballistic-to-diffusive transition (similar to 4.05 m). Our findings advance the understanding of orbital current transport in ferromagnetic metals and pave the way to designing novel functional orbitronics devices.

Super exchange interactions are pivotal to understanding the magnetism of complex ferrites. In this study, the electronic structure, magnetism, and superexchange interactions of Co2Z (Ba3Co2Fe24O41) were calculated using density functional theory (DFT) with the GGA + U method. The results indicate that Co2Z exhibits semiconductor properties, with Fe3+ ions in all sublattices in a high-spin state. The band structure reveals strong hybridization between Fe 3d and O 2p orbitals, which forms the basis for the Fe-O-Fe super exchange interactions. Importantly, the exchange mechanism between all sublattices is antiferromagnetic, though the strength of the exchange interactions varies due to spatial differences among the sublattices, there is a strong exchange interaction between the sites 2a and 4f2*, 2d and 4f1. Moreover, the Curie temperature calculated (545 K) from the exchange integrals is close to the experimental value (600 K).

Spectrally selective infrared absorbers play a pivotal role in enabling optoelectronic applications such as infrared detection, thermal imaging, and photothermal conversion. In this paper, a dual-band wide-spectrum infrared selective absorber based on a metal–dielectric multilayer structure is designed. Through optimized design, the absorptance of the absorber reaches the peak values of 0.87 and 1.0 in the target bands (3–5 μm and 8–14 μm), while maintaining a low absorptance of about 0.2 in the non-working bands of 5–8 μm, with excellent spectral selectivity. By analyzing the Poynting vector and loss distribution, the synergistic mechanism of the ultra-thin metal localized enhancement effect, impedance matching, and intrinsic absorption of the material is revealed. This structure exhibits good polarization-insensitive characteristics and angle robustness within a large incident angle range, showing strong adaptability to complex optical field environments. Moreover, the proposed planarized structure design is compatible with standard fabrication processes and has good scalability, which can be applied to other electromagnetic wave bands. This research provides new design ideas and technical solutions for advanced optoelectronic applications such as radiation cooling, infrared stealth, and thermal radiation regulation.

Soft magnetic multi-principal element alloys (SMMPEAs) are emerging as promising materials for magnetic components in electrical applications and sustainable energy supply. However, achieving both excellent mechanical properties and soft magnetic properties remains a challenge for SMMPEAs. Here, the “metastability engineering” strategy is exploited in SMMPEAs to overcome the strength–ductility trade-off via the transformation-induced plasticity (TRIP). The designed alloy has a tensile strength of 1.65 GPa at 15% tensile elongation, saturation magnetization of 131 emu/g, coercivity of 12.5 Oe, and electrical resistivity of 116 μΩ cm. The results herein provide an effective paradigm for developing metastable SMMPEAs with TRIP for an enhanced strength–ductility synergy, paving the way for their application of high-performance magnetic components.

The photocatalytic efficiency of bismuth-based metal-organic framework (Bi-MOF) is extremely restricted by the rapid recombination of photogenerated electron-hole pairs, which reduce the number of electrons involved in the photocatalytic reduction reaction. Constructing precise interfacial bond bridges between metal nanoparticles (NPs) and MOFs has emerged as an effective strategy to address the above-mentioned issues, promoting the electrons transfer. Herein, this study improves the sluggish dynamics of photogenerated charge in Bi-MOF by inducing the Pd-O-Bi bond bridges at the interface on a Pd NPs-decorated Bi-MOF (Pd/Bi-MOF) nanosheets. This phenomenon results in an interaction between Pd NPs and the Bi-MOF support. And Pd-O-Bi bond bridges provide the fast electron transfer channels, triggering the directional migration of photogenerated electrons from Pd to Bi node, then enhancing the spatial separation of photogenerated electron-hole pairs, finally facilitating overall photocatalytic CO2 reduction. The presence of these bond bridges leads to higher enhancement in CO production for Pd/Bi-MOF nanosheets compared to the Bi-MOF nanosheets under visible light irradiation after 4.5 h. This research demonstrates the importance of interfacial bond bridges and provides a reasonable guide to design efficient photocatalyst for reduction of CO2 to CO.

Nonmagnetic-metal/ferromagnetic heterostructures have drawn extensive attention due to the generation of spin–orbit torque (SOT). This work is based on the large spin Hall angle observed in Pt0.70(GdOy)0.30 composite films, we focus on investigating the sharp sign reversal of the damping-like SOT induced by antiferromagnetic coupling at the NiFe/Pt1−x(GdOy)x (x ≥ 0.30) interface. Such interface-modulated SOT is found to be suppressed by inserting an ultra-thin copper spacer layer using spin-torque ferromagnetic resonance. Meanwhile, the relevant interfacial parameters further indicate the key importance of interfacial magnetic coupling for boosting spin transport efficiency. The superconducting quantum interference device tests on NiFe/Pt1−x(GdOy)x (x ≥ 0.30) structures reveal that the magnetization in Pt1−x(GdOy)x is antiparallel to that of NiFe, forming an antiferromagnetically coupled configuration at the NiFe/Pt1−x(GdOy)x interface. Our results highlight the promising application of rare earth materials in spin transport, and the construction of interfacial antiferromagnetic coupling opens a route to modulate SOT.

We have discovered that charge transfer in ferrites can be highly advantageous. This study, combining experimental methods and theoretical calculations, investigates the charge transfer that occurs when light rare-earth (RE3+) ions substitute for Ba2+ ions in Co2Z, partially converting Fe3+ to Fe2+. The formation of Fe2+ enhances magnetic anisotropy, thereby increasing the cutoff frequency of Co2Z. Our findings indicate that these rare-earth elements share similar properties: they preferentially occupy the Ba (2b) site, causing a slight reduction in lattice constants due to differences in ionic radii, and charge transfer occurs at the Fe (12k*) sites. Although this charge transfer does not significantly alter the saturation magnetization (Ms), the stronger spinorbit coupling (SOC) associated with Fe2+ significantly enhances magnetocrystalline anisotropy, particularly in the case of La-Co2Z. As a result, the natural resonance frequency of Co2Z is increased from 2.39 GHz to 3.15 GHz. This improvement is highly beneficial for high-frequency applications.

Spintronic terahertz (THz) emitters composed of nanoscale-thick ferromagnet/heavy metal multilayer structures exhibit an outstanding capability to generate high-quality, broadband THz pulses. However, there is a lack of research on laser-excited ultrafast spin current generation and manipulation in flexible nanoscale-thick magnetostrictive film/heavy metal heterostructures. Thus, we investigate photoinduced and strain-induced spin currents in flexible nanoscale-thick magnetostrictive film/heavy metal heterostructures employing THz emission spectroscopy. Under femtosecond laser excitation, ultrafast magnetization precession with a long lifetime is induced by photoinduced short strain waves in the magnetoelastic heterostructure due to magnetoelastic coupling. We observe a modulation in THz amplitudes with increasing external magnetic field strength, which aligns well with theoretical models based on magnetoelastic coupling in flexible magnetoelastic heterostructures. Specifically, we demonstrate how the strength of magnetoelastic coupling energy exchange affects ultrafast spin currents. Our work offers a significant method to advance the development of spintronic THz emitters based on nanoscale-thick magnetoelastic materials.

Orbital current refers to the flow generated by transmitting the orbital angular momentum of electrons. Compared to spin current, orbital current exhibits distinct advantages, including lower critical current density for magnetization switching, longer propagation distances, and enhanced stability in high-temperature environments. However, the effective utilization of orbital currents remains underexplored. This study reports a giant torque efficiency in Sm/Pt metallic heterostructures, enabling highly efficient magnetization switching. Spin-torque ferromagnetic resonance measurements reveal a tenfold enhancement in torque efficiency ( xi = 0.10 +/- 0.02) for the Sm/Pt/Py system compared to Pt/Py. This enhancement originates from the dominant contribution of orbital current. Furthermore, the Sm/Pt/Co/Pt heterostructure exhibits a low critical switching current density (J(sw+) < 3.98 x 10(6) A/cm(2)), demonstrating a tenfold improvement in switching efficiency over conventional Pt/Co/Pt systems. We have also achieved field-free switching across all tested thicknesses of the Sm. These metallic heterostructures, combining large effective orbital Hall angles, low thermal dissipation, and compatibility with semiconductor integration, hold significant promise for large-scale applications in orbitronic devices.

Femtosecond photoexcitation can abruptly redistribute electrons and trigger a series of transient nonequilibrium processes, among which ultrafast interatomic forces play a pivotal role in determining the structural and functional characteristics of solids. While ultrafast interatomic forces and their associated lattice dynamics have been extensively examined in semiconductors, experimental investigations of these nonequilibrium dynamics in metals remain lacking. To address this scientific gap, herein the direct observation of femtosecond‐scale variations in photoinduced ultrafast interatomic forces within wrinkled giant magnetostrictive FeGa thin films is presented. At the onset of demagnetization, a transient signal emerges, lasting ≈400 fs, with its orientation is influenced by the external magnetic field. Theoretical analysis indicates that this signal arises from the swift release of internal stress prompted by the suppression of magnetostriction during ultrafast demagnetization. Owing to magnetization‐induced stress anisotropy, this transient alteration in the interatomic potential introduces additional birefringence to the probe light. Consequently, this signal is attributed to a transient distortion of interatomic forces induced by the abrupt electron redistribution, establishing a nonequilibrium force state before any observable lattice expansion. These findings provide direct evidence for the existence of sub‐picosecond interatomic forces and suggest a novel approach to control metal lattice dynamics through ultrafast magnetostriction.

The splitting phenomenon of ferromagnetic resonance (FMR) spectra of Ni80Fe20(NiFe) films deposited on periodically rippled sapphire substrates is studied experimentally with the help of micromagnetic simulation. The analyses show that the splitting of FMR spectra is related to the periodic ripple topography of films. When the applied magnetic field is perpendicular to the ripple direction, the effective field of periodically rippled films becomes inhomogeneous. The splitting of FMR spectra originates from localized FMR peaks corresponding to different regions with different effective field intensities in the rippled structure. Furthermore, the relative intensity and position between the split mode and the main FMR mode can be changed by designing ripple topography. This work would help understand the splitting phenomenon of FMR spectra for magnetic thin films deposited on the periodically rippled sapphire substrates.

Crystal structure, microstructure, static and dynamic magnetic properties of Ba3-xNdxCo2Fe24O41 3-x Nd x Co 2 Fe 24 O 41 (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) ceramics were investigated. Samples were prepared via sintering at 1250 degrees C for 4 h, and XRD results revealed their crystal structure after Nd substitution. With the increase in Nd3+ 3+ ion dopant content, particle porosity increased, leading to slight decrease in volume density. Static magnetic data showed the weak effect of Nd-substitution on saturation magnetization strength and a slight increase in coercivity (from 52 Oe to 75 Oe at x = 0-0.5), while out-of-plane magnetic anisotropy rose significantly (from 10.1 kOe to 14.5 kOe at x = 0-0.5). Dynamic magnetic tests demonstrated noticeable decrease in permeability (from 17 to 8), whereas cutoff frequency increased from 0.8 GHz to 1.9 GHz and the maximum Snoek product reached 18.8 GHz for the sample with x = 0.4. The fitting of real part of permeability using domain wall resonance and natural resonance models revealed that resonance frequency and out-of-plane anisotropy both increased with Nd-substitution. Moreover, despite Nd doping, samples maintained low magnetic loss and high Q value within higher frequency range. Therefore, findings of this study provide a pathway to development of substituted Z-type barium (Co2Z) 2 Z) ferrites for high frequency applications.