Research articles

The tetragonal Mn_3-xPd_xGa becomes compensated ferrimagnet at x = 0.7. In the compensated ferrimagnet, Mn_2.3Pd_0.7Ga, we observed spin reorientation and topological Hall effect due to the strong spin-orbit coupling and inversion symmetry breaking by Pd atoms. We revealed that this additional Hall behavior is attributed to non-collinear spin configuration such as magnetic skyrmions. Our observations are expected that Mn-based compensated ferrimagnets are promising and will open a new avenue toward spintronic high-density and low-power devices.

In this study, we present a novel nanoparticle with a nanoneedle-assembled shell and a magnetic core, which has great advantages over other materials used for exosome enrichment. Besides, the potential value of this nanoparticle in the enrichment and assay of exosomes has not been studied yet. The bio-inspired hierarchical nanoparticles could serve as an excellent platform for the effective capture and detection of exosomes. Thus, we believe that these novel nanoparticles are promising candidates for biological isolation and tumor diagnosis.

In ferroelectric MOSFETs, the reduced subthreshold swing (SS) below Boltzmann limit has attracted great attention due to its potential in decreasing power consumption. Here, through tuning the ferroelectric switching dynamics of BiFeO₃ ferroelectric capacitor, the SS of a commercial MOSFET connected with the ferroelectric capacitor is significantly reduced to be zero over seven decades of the drain current. Interestingly, the SS can even be further tuned to be negative, i.e., the drain current increases with decreasing gate voltage. The intriguing strategy to control SS from positive to negative is promising for designing advanced MOSFETs with ultralow and tunable SS.

We found new phonon vibration modes in formamidinium (FA)-based hybrid perovskite structures. We intriguingly found that the δ/α-mixed-phase exhibited significant THz-wave absorption peaks at 2.0 and 2.2 THz that were not related to any phonon modes from either the δ- or α-phases, although the δ/α-mixed-phase sample was confirmed to be formed by a physical combination of the δ- and α-phases without the creation of any new chemical states. From the theoretical study, they originate from the novel vibration modes excited at the seamless interfaces in the mixed phase of FAPbI₃.

We find a very large field-like spin-orbit torque in a bulk Rashba channel/ferromagnet structure and this large value of spin-orbit torque is attributed to the interfacial spin-orbit coupling enhanced by the well-grown bulk Rashba material.

Combining molecular dynamics and finite element modeling, a possible mechanism of the moisture-induced shape memory effect of wood cell walls is explored, emphasizing the role of interface mechanics, a factor previously overlooked. Upon wetting, the interface is weak and soft, and the material can be easily deformed. Upon drying, the interface becomes strong and stiff, and composite deformation can be locked. When the interface is wetted again and weakened, the previously locked deformation cannot be sustained, and recovery occurs. The elastic energy and topological information stored in the cellulose fiber network is the driving force of the recovery process.

Schematic illustration of functional injectable hydrogel system for cartilage regeneration. (1) Preparation of hydrogel with the function for spatiotemporal releasing SDF-1 and KGN; (2) Spatiotemporal regulation of MSCs recruitment and chondrogenic differentiation by hydrogel in vitro; (3) Implantation of hydrogel and cartilage regeneration.

We investigate how random scattering modulates the optical properties, from terahertz to ultraviolet, of a three-dimensional graphene network based on interconnected high-quality 2-Dimensional graphene layers. We show how the connectivity and morphology of these materials allow a broadband interaction with light. The 3D graphene networks behave like a high-pass optical filter due to spatially multiscale random scatterers, corresponding to pores and graphene branches in the 3D network. We develop a model based on the Radiative Transfer theory describing the interaction of the network with light, from which we estimate the photon scattering mean free path.

3D printing of bioceramic-induced macrophage exosomes (BC-Exos) displayed stimulatory effects on immunomodulation, osteogenesis, and angiogenesis of macrophage (MΦs), mesenchymal stem cells (MSCs) and endothelial cells (ECs), respectively. BC-Exos enhanced the expression of chemotaxis, osteogenic and angiogenic genes by altering their miRNAs profile. 3D printing of BC-Exos offers a new cell-free strategy for tissue regeneration.

The introduction of minimal Ni into MnCoSi efficiently changes the magnetic interaction and establish a thermal-induced magnetic transition from a spiral magnetic state to a ferromagnetic-like state in Mn_1-xNi_xCoSi alloys. With increasing the temperature, both the cycloidal and helical magnetic spin rotates continuously and coherently towards to b axis during the transition. Therefore, a wide-temperature range zero thermal expansion behaviour is realized owing to the robust magnetoelastic coupling.

We provide a conclusive demonstration of strain-induced room-temperature ferroelectricity in SrMnO₃ thin films by securing samples with insulating properties and clean surfaces using selective oxygen annealing. These findings will not only provide a cornerstone for exploring the physical properties of multiferroic SrMnO₃ but will also inspire new directions for single-phase multiferroics.

A classification of Fe-pnictide heterointerfaces based on electrostatic principles into initially compensated and uncompensated interfaces is proposed and used for tailoring the interfacial microstructure and superconducting properties. We show that the heterointerface between LnOFeAs (Ln = La, Sm) and BaFe₂As₂ is nonpolar and remains clean and coherent with Co²⁺ addition. Co-diffusion results in superconductivity across the whole bilayer. In contrast, IFL formation occurs after adding O²⁻, and superconductivity with a 2D signature develops with time.

The dependence of the afterglow in millisecond time scale and light yield (in the inset) on the Gd content in the Gd_xLu_1-xAlO₃ single crystal scintillator.

High critical current density and strong pinning efficiency for Fe-based superconductor, K-doped BaFe₂As₂, were achieved by naturally formed low-angle grain boundary networks. K-doped BaFe₂As₂ thin film is composed of columnar grains with widths of approximately 30–60 nm. The grains are rotated around the b- (or a-) axis by 1.5° and around the c-axis by −1°, resulting in the formation of low-angle grain boundary networks. The achieving superconducting properties are almost 10 times as high as the K-doped BaFe₂As₂ single crystal and comparable to ion-irradiated single crystal.

This paper reports a voltage-controlled nonvolatile 90° magnetization rotation and voltage-assisted 180° magnetization reversal in a spin-valve multiferroic heterostructure. By using the strain-mediated magnetoelectric coupling effect, the magnetic moment of the free layer can be manipulated by an electric field. The critical magnetic field required for complete 180° magnetization reversal can be tremendously reduced. Accordingly, a large and nonvolatile magnetoresistance modulation was achieved.

The timely and continuous measurement of cortical maps is required for studying the nature and plasticity of brain maps. In this work, we developed the multichannel graphene array that enables high-resolution brain mapping, facilitating rapid and repetitive assessments of brain maps. The advanced graphene array with intervening thru-hole enables large-scale mapping simultaneously in the surface and deep of cortical areas, also improving conformality for better detection of electrocorticography signals. In a subset of the graphene array, cortical surface stimulation can remodel cortical maps, therein enhancing cortical plasticity. This technology provides potential therapeutic applications for various brain disorders by correcting brain maps.

A shape-variant heat dissipation system using kirigami was proposed using the thermally conductive cellulose nanofiber films. By stretching the Amikazari (net decoration) pattern produced by kirigami and allowing air convection through its aperture at 3.0m/s, the thermal resistance was reduced to approximately one-fifth of that without kirigami and convection. The periodic apertures of kirigami defined the outlet air velocity of convection, resulting in a significant increase in the heat-transfer coefficient. We further demonstrated the effective cooling of the kirigami-processed powder electroluminescent device during the emission of light.

Multiferroic lead-doped barium hexaferrite exhibits remarkably rich set of phenomena at frequencies from Hertz to near infrared, including tunable terahertz resonance. Unveiling microscopic mechanisms responsible for such extraordinary response paves the way for controllable tuning of the functional characteristics of the material demanded by next-generation terahertz electronics.

Significant size effect and stress fluctuation of nanoscale lamellar bone pillars with diameters ranging from 640 to 4971 nm inside a single lamella. A size effect-induced brittle-to-ductile transition was revealed, the stress fluctuation behaviors were elaborated through a layered dislocation movement theory on the basis of strain gradient plasticity theory.

Based on the first-principles calculation on the β-W based alloy structure using Ta and V, we have introduced the W–Ta and W–V alloy in between the β-W/CoFeB layer. Through the harmonic response method, we confirmed that experimentally obtained spin-Hall conductivity has fairly similar alloy compositional dependence with the theoretically calculated one. Particularly, when W₈₀V₂₀ alloy was placed at the β-W/CoFeB layer, the spin Hall conductivity reached (−2.77 ± 0.31) × 10³ S/cm, which enhanced over 36% compared to the pristine β-W/CoFeB/MgO heterostructure.