Physical sciences articles within NPG Asia Materials

Featured

  • Article
    | Open Access

    A facile chemical vapor method is developed for large-scale synthesis of CsPbX3-ZSM-5 composites. Owing to the effective confinement and encapsulation of CsPbBr3 QDs by ZSM-5, the composites possess excellent photophysical properties and ultrahigh stability. The prepared composites are applied in white light-emitting diodes (WLEDs) and multicolor-coded anti-counterfeiting inks. This technique provides the probability for commercial production of these perovskite composites with robust stability.

    • Tongyu Shi
    • , Xi Chen
    •  & Xue-Feng Yu

  • Article
    | Open Access

    A magnetic superhydrophobic tubular actuator for water transport has been designed and successfully demonstrated. Under the control of an externally applied magnetic field, the actuator could deform correspondingly and propel the water droplet in the tube to move forward with a high speed up to 16.1 cm/s, which is the highest velocity measured for water transport in a closed actuator system. Several representative liquids (i.e., phosphate buffer solution, artificial urine, and sweat) widely used in biomedical engineering have also been achieved to transport in the tubular actuator with negligible liquid loss under an applied magnetic field.

    • Fangyihan Xiong
    • , Liyun Zhang
    •  & Fan Xia

  • Article
    | Open Access

    A very active research area in superconductivity is the performance improvementofthe current carrying capability (Jc). Here, we show that the depairing current (Jd) can beincreased by controlling the penetration depth (λ) and coherence length (ξ) in the two most representative materials: in REBa2Cu3Oy we increased the carrier density to decrease λ and ξ, and in BaFe2(As1-xPx)2 we tuned the chemical pressure. The combination ofthese thermodynamic and flux-pinning optimization routes leads to a dramatic increase of Jc to Jc ~150 MA/cm2 at 4.2 K (32.4% of Jd) for REBa2Cu3Oy, the highest value ever reported for any superconductor.

    • Masashi Miura
    • , Go Tsuchiya
    •  & Boris Maiorov

  • Article
    | Open Access

    High quality thin films of the intrinsic magnetic topological insulator MnBi2Te4 were studied by means of optical spectroscopy in a broad spectral range from THz to UV. By analysing the optical conductivity at room temperature for different thickness, the presence of surface topological states superimposed to the bulk electrodynamics response was highlighted. For the thinnest film, where charge transport is dominated by the Dirac surface states, the interplay between the magnetic phase transition and the topological surface states was investigated. Crossing the Neèl temperature, the optical conductivity measurements indicate the opening of a magnetic gap at the Dirac node

    • Luca Tomarchio
    • , Lorenzo Mosesso
    •  & Stefano Lupi

  • Article
    | Open Access

    Our experiments and ab initio calculations demonstrate that a defect dipole (μdef) composed of Cu3+ and oxygen vacancy in a ferroelectric BaTiO3 ceramic is coupled with spontaneous polarization (Ps). By designing an arrangement μdef, a shifted polarization (P)-electric field (E) loop is obtained because of the strong interaction between μdef and Ps. The resultant ferrorestorable polarization delivers an extraordinarily large effective relative permittivity, beyond 7,000, with a high recoverable energy density (Urec) and efficiency. This work paves the way to realizing efficient energy storage ceramic capacitors for self-powered applications.

    • Hiroki Matsuo
    • , Masashi Utsunomiya
    •  & Yuji Noguchi

  • Article
    | Open Access

    In this work, an anticancer drug, metformin, has been used to promote DNA single strands to assemble into well-defined DNA nanostructures. The resulting metformin-DNA complex nanostructures can simultaneously deliver metformin and KRAS siRNA to synergistically treat KRAS-mutated, non-small cell lung cancer in vivo.

    • Hang Qian
    • , Dong Wang
    •  & Guansong Wang

  • Review Article
    | Open Access

    Palladium (Pd)-nonmetal nanostructures, as a special class of Pd-based alloys, have exhibited diversified advantages for fuel cell reactions. This minireview summarized the most recent progress in the synthesis of Pd-nonmetal nanostructures and their applications in fuel cells. Especially, this review proposed the promising strategies for enhancing the performance of Pd-nonmetal nanostructures in fuel cell applications. It is expected that this review will generate more research interest in the development of more advanced Pd-nonmetal nanocatalysts.

    • Mengjun Wang
    • , Leigang Li
    •  & Xiaoqing Huang

  • Article
    | Open Access

    Biohybrid micro/nanorobots that integrate biological entities with artificial nanomaterials have shown great potential in the field of biotechnology. Here, the magnetic plant biobots (MPBs) were fabricated by employing tomato-callus cultivation engineering in the presence of Fe3O4 nanoparticles that are capable of active movement and directional guidance under a transversal rotating magnetic field. The MPBs enabled rapid and efficient removal of chlorpyrifos (approximately 80%), a hazardous nerve gas agent that causes severe acute toxicity, and recovery using an external magnetic field. The eco-friendly plant biobots described here demonstrate their potential in environmental applications.

    • Su-Jin Song
    • , Carmen C. Mayorga-Martinez
    •  & Martin Pumera

  • Article
    | Open Access

    The first prototype of the portable protein analyzer made with liquid crystal polymer microtubes is constructed to perform the processes of suspending, depositing, and separating for protein extraction and detection by combined photo/magnetic control. Such an analyzer specifically purifies, enriches, and detects various proteins in complex samples in a short time (20 min) and with trace sample consumption (5 μL) and a low detection limit (1 μg mL-1).

    • Yao Lu
    • , Lang Qin
    •  & Yanlei Yu

  • Article
    | Open Access

    Solid-phase crystallized Ce and H codoped In2O3 (ICO:H) transparent conducting films achieve very high electron mobility values of over 100 cm2/Vs and suitable low-carrier concentration, leading to high electrical conductivity and broadband optical transparency. However, a high-temperature annealing process for solid-phase crystallization is necessary to obtain high mobility. Therefore, such a high processing temperature limits the formation and adoption of these films on heat-sensitive flexible substrates. Herein, we used excimer laser irradiation to achieve an ICO:H film on flexible polyethylene terephthalate that had ultrahigh mobility of 133 cm2/Vs, which is the highest among those reported for flexible transparent electrodes.

    • Junichi Nomoto
    • , Takashi Koida
    •  & Tetsuo Tsuchiya

  • Article
    | Open Access

    Two-dimensional (2D) van der Waals (vdW) magnet with the advent of ferromagnetism has stimulated particular attention in exploring topological spin texture especially for skyrmions. We here report the real-space observation of tuning the density of field free skyrmions in Fe3GeTe2(FGT), which can serve as a new application for spintronic devices. By tilting the FGT nanosheet, we found that the field-free Bloch-type skyrmions can also represent an invisible contrast when the tilt angle is zero, but emerge a reversal magnetic contrast at high tilt angle. These findings shed light on the identification of the spin configuration in 2D vdW magnet.

    • Bei Ding
    • , Xue Li
    •  & Wenhong Wang

  • Article
    | Open Access

    X-ray magnetic tomography measurements were performed on an advanced high-coercivity Nd-Fe-B permanent magnet, and three-dimensional (3D) magnetic domain structure was successfully obtained along the magnetic hysteresis curve. Furthermore, scanning electron tomography measurement was adopted to obtain 3D microstructure for the same observing volume. By comparing these two types of 3D images, we found various critical behaviors of magnetic domains inside the magnet, which are essential to understand the microscopic coercivity mechanism of permanent magnets.

    • Makoto Takeuchi
    • , Motohiro Suzuki
    •  & Satoshi Okamoto

  • Article
    | Open Access

    Potassium acetate (KAc) has desirably both a high solubility and a salting-out effect on polyvinyl alcohol (PVA). The freezing temperature of 50 wt% KAc solution can reach as low as −70 °C. The hydrogels soaked in 50 wt% KAc solution exhibit the highest mechanical properties with an ultimate stress of 8.2 MPa and toughness of 25.8 MJ/m3, surpassing most reported results for anti-freezing gels. At 50 wt% KAc, the hydrogels also present a high conductivity of 8.0 S/m at room temperature and 1.2 S/m at −60 °C.

    • Shuwang Wu
    • , Ta-Wei Wang
    •  & Ximin He

  • Article
    | Open Access

    Though collinear-type antiferromagnets are fundamental building blocks of antiferromagnetic (AFM) spintronics, the potential utilization of non-collinear-type antiferromagnets for spintronic functionality has not been elucidated thus far. Here we suggest an AFM helimagnet of EuCo2As2 as a novel spintronic material, revealing an unconventional sign-changing behavior of anisotropic magnetoresistance. This contrast arises from electrically distinctive dual magnetic phases. Further, various AFM memory states regarding magnetic-phase evolution were identified by combining experimental and theoretical results. Our findings based on a unique type of AFM order are useful for the development of AFM spintronics, which has been driven by new materials.

    • Jong Hyuk Kim
    • , Hyun Jun Shin
    •  & Young Jai Choi

  • Article
    | Open Access

    We report a new type of mesh electrode based on metal/oxide-based elastic films such as indium zinc oxide (IZO) with high transparency and low diffraction for highly stretchable organic light-emitting diodes (SOLEDs). Furthermore, the electrical, optical, and mechanical performances of the IZO mesh electrode are further enhanced by incorporating island-shaped Ti nanoparticles beneath the IZO mesh [i.e., 22 Ω/sq., 92% at 480 nm, mechanical stability under 100% strain and 1000 endurance cycles]. TADF-based blue SOLED with the proposed Ti-embedded IZO mesh electrode exhibits a stable operation with a high external quantum efficiency of 13.2% and a 100% stretchability.

    • Tae Hoon Park
    • , Wanqi Ren
    •  & Tae Geun Kim

  • Article
    | Open Access

    We propose a gravity-assisted rotatory drawing method to fabricate multicolor lasing microfibers, and weave them into flexible textiles. Through regulating the doped dyes and solution viscosity, full-color tunable lasing textiles can be achieved. Furthermore, nanoparticle patterns are printed on the lasing textile to encrypt it for anticounterfeiting application.

    • Jun Ruan
    • , Dan Guo
    •  & Tianrui Zhai

  • Article
    | Open Access

    Self-propelled amorphous, cubic, and tetrahedral Ag3PO4 micromotors were synthetized using a scalable precipitation method for antibacterial applications. Their programmable morphologies exhibited different motion properties under fuel-free and surfactant-free conditions and visible light irradiation. Differences in these motion properties were observed according to morphology and correlated with photocatalytic activity. Ag3PO4 micromotors are inherently fluorescent. The as-prepared self-propelled particles exhibited morphologically dependent antibiofilm activities toward eradication of gram-positive and gram-negative bacteria.

    • Daniel Rojas
    • , Michaela Kuthanova
    •  & Martin Pumera

  • Article
    | Open Access

    We first show through computational simulations and experiments that mechanochromic molecules, spiropyrans (SPs), were activated by force in Diels–Alder (DA) reaction-based CANs. Owing to the mechanochromic SP molecules and thermally reversible DA networks, these thermosets indicated damage with colour and fluorescence signals and autonomously repaired it with thermal treatment. While maintaining high solvent resistivity and good mechanical performance, they were reprocessed up to fifteen times without degrading the mechanical, damage-reporting, and self-healing properties.

    • Subin Yoon
    • , Jong Ho Choi
    •  & Tae Ann Kim

  • Article
    | Open Access

    Plasmonic thin-layer chromatography was developed for the separation of quantum dots (QDs) by combining plasmonic optical trapping with thin-layer chromatography (TLC). Photoexcitation of the localized surface plasmon resonance of Au nanoparticles immobilized on a TLC plate decreased the distance traveled by QDs, enabling size separation of QDs with identical compositions and sorting of QDs according to the optical properties of QDs with the same size. Optical property-based separation cannot be achieved by conventional chromatography, in which the interactions between stationary phases of chromatographs and QDs are simply based on the differences in the size or surface functionality of QDs.

    • Tsukasa Torimoto
    • , Naoko Yamaguchi
    •  & Yasuyuki Tsuboi

  • Article
    | Open Access

    Glasses are non equilibrium materials that develop by cooling of a supercooled liquid, where the rapidly increasing viscosity results in a kinetic arrest of long range atom rearrangements. During heating from glass state, different relaxations are thermally activated and display different relaxation spectrum. Here, we used one ultrafast nanocalorimetry to examine the evolution of multiple relaxations and discover the merging of the relaxation modes with increasing heating rates, resulting in step-like increases in both the supercooled liquid region and excess heat capacity. Our findings provide new insights on the evolution of the relaxation spectrum and the associated heterogeneous atomic motion.

    • Meng Gao
    •  & John H. Perepezko

  • Perspective
    | Open Access

    This Perspective illustrates how theory and experiment can be combined to study the interfacial charge transfer between transition metal nanoparticles and oxide supports, the short- or long-range natures of interactions between them and the effects of oxide nanostructuring on the properties of supported metal particles. These studies deepen our understanding of the role of metal-oxide interactions in industrially relevant nanocomposites thus helping to design interfaces with unique properties for future applications

    • Konstantin M. Neyman
    •  & Sergey M. Kozlov

  • Article
    | Open Access

    Charge carrier modulation in graphene by proximate ferroelectricity has attracted much attention, but it was rarely successful especially for oxide ferroelectrics mainly due to uncontrolled interfacial charge traps. In this work, the device operation of field–effect transistor comprising of graphene and ferroelectric single-crystal Pb(Mg1/3Nb2/3)O3–PbTiO3 was carefully analyzed for studying the direct or indirect coupling phenomena between charge carriers in graphene and nearby ferroelectricity.

    • Nahee Park
    • , Hyunkyung Lee
    •  & Dongseok Suh

  • Article
    | Open Access

    Stickable light-emitting diodes (LEDs) were fabricated by selectively growing GaN micro-LEDs on a graphene sheet. Using the van der Waals interaction of the bottom graphene layer, the micro-LED/graphene heterostructures uniformly adhered to foreign graphene films. The transferred LEDs were fully operational and maintained good mechanical adhesion and electrical connections to the foreign graphene films under various bending conditions. Since the van der Waals integration method provides simple assembly processes of heterogeneous materials with negligible material compatibility issues, the LED/graphene heterostructure will be capable of integrating with various 2D devices.

    • Anuj Kumar Singh
    • , Kwangseok Ahn
    •  & Kunook Chung

  • Article
    | Open Access

    The effects of nanomorphologies of acceptors on the environmental stability of donor:acceptor blends were investigated. Dispersed acceptors in mixed phase accelerate the photooxidation of donor, whereas aggregated acceptors stabilize the donor, both of phenomena coinciding for blends. Furthermore, photooxidation of donor leads to significant deterioration of hole transport, which shows strong correlation with efficiency loss in donor:acceptor organic solar cells.

    • Woong Sung
    • , Hansol Lee
    •  & Kilwon Cho

  • Article
    | Open Access

    We developed multi-bishelled cobalt-based nanospheres with each bi-shelled structure consisting of symmetric heterogeneous configuration. This architecture features sufficient heterointerfaces and a high density of active sites benefiting from interfacial electronic modulation. When they worked as OER electrocatalysts in CO2 electrolysis, the electrochemical performance of Pd nanosheets (NSs) for CO2 reduction can be significantly enhanced in terms of product selectivity and energy input.

    • Yu Zhang
    • , Penglun Zheng
    •  & Qingyu Yan

  • Article
    | Open Access

    We, for the first time, reveal that manipulation of microstructure enables the suppression of phase transformation and enhancement of long-term stability of Bi2O3-based ionic conductors. To investigate the microstructural influence on the stability, thin films with precisely defined grain structures are prepared. The conductivity of polycrystalline thin film decreased by 94.6% after approximately 20 h of operation, while the initial conductivity of epitaxial thin film remained almost constant during annealing for up to 100 h. This study provides novel insights for the development of highly conductive and durable solid electrolytes for next-generation energy applications.

    • Incheol Jeong
    • , Seung Jin Jeong
    •  & Kang Taek Lee

  • Article
    | Open Access

    Two-dimensional (2D) silicon sample consists of an airy hole array in a crystalline silicon thin film matrix was designed and fabricated with the property of phononic crystal. Significant suppression of hot carrier cooling was observed with lifetime prolongation by orders of magnitude. The present direct experimental evidence for hot carrier cooling suppression in 2D silicon phononic crystals and opens opportunities for promising applications.

    • Wensheng Yan
    • , Liyuan Long
    •  & Guijie Liang

  • Article
    | Open Access

    Sialylated glycans (SGs), abundant in cell membranes, play decisive roles in regulating ion channels (e.g., NaV1.4, KV1.1, CaV1.2) in life system, only when the ion channels work stably and accurately can life activities proceed normally. Here we construct a biomimetic SG-modulated nanochannel based on a smart polymer design. Carbohydrate‒carbohydrate interaction triggers globule-to-coil transition of the polymer chains, which regulated the dynamic ion gating behavior of this nanochannel, resulting in a significant reduction in transmembrane ionic current. This device exhibits excellent specificity and sensitivity in response to α-2,6-linked sialyllactose, further realizing real-time monitoring of the sialylation reaction catalyzed by α2,6-sialyltransferase.

    • Jie Xiao
    • , Wenqi Lu
    •  & Guangyan Qing

  • Article
    | Open Access

    In this work, a high-Tc (~117 K) joined with a high-Jc (>104 A/cm2, 100 K) are reported in the CuBa2Ca3Cu4O10+δ (Cu-1234) superconductor. Studies have shown that the ordering vacancies and platelike 90° micro-domains serve as efficient microstructure pinning centers which suppress the vortex flux flow and enhance Jc. And plenty of holes with 2pz symmetry owing to unique compressed [CuO6] octahedrons decrease superconducting anisotropy and enhance the interlayer coupling that guarantee a high-Jc.

    • Xuefeng Zhang
    • , Jianfa Zhao
    •  & Jing Zhu

  • Article
    | Open Access

    The photoactive α-phase FAPbI3 perovskites can spontaneously transform into δ-FAPbI3, which limits its use in photovoltaic device field. In this work, we show that the incorporation of the dimethylamine cation into FAPbI3 significantly improves phase stability and photoelectric response of FAPbI3 perovskite materials, while the inherent bandgap energy of the FAPbI3 perovskite is maintained. A detailed 2H NMR analysis reveals the property optimization attributes to the increase of coupling interaction between organic cations and inorganic lattice.

    • Wen-Cheng Qiao
    • , Jia-Qi Liang
    •  & Ye-Feng Yao

  • Article
    | Open Access

    We synthesized small-sized ion doped PEDOT-Ag quantum dot (S-PEDOT-Ag QD) composite film via one-step vapor phase polymerization (VPP) using a novel Ag(I) salt precursor. The films exhibit enhanced thermoelectric performance and good antibacterial activity at low Ag loadings. This facile approach provides new route to synthesize high performance conducting polymer–inorganic composite.

    • Wei Shi
    • , Qin Yao
    •  & Lidong Chen

  • Review Article
    | Open Access

    This review focuses on the electron-phonon interactions in lead halide perovskite semiconductors, which dominate their optical and electronic properties by forming polarons. We describe the uniqueness of perovskite semiconductors in terms of long-range and short-range electron-phonon interactions. The formation of polarons profoundly affects the carrier effective mass, mobility, and various optoelectronic properties. These topics are explained with recent experimental data.

    • Yasuhiro Yamada
    •  & Yoshihiko Kanemitsu

  • Article
    | Open Access

    An illustration of the optically controlled entanglement between a radical spin and a triplet state on an optically active moiety such as a phthalocyanine molecule. The optical excitations and the resulting strong exchange interactions, in combination with the recent spin manipulation in molecules at high temperature, imply this entangling mechanism has a great potential for room temperature quantum computing.

    • Lin Ma
    • , Jiawei Chang
    •  & Hai Wang

  • Article
    | Open Access

    We show giant converse magnetoelectric effect in a multiferroic heterostructure consisting of ferromagnetic Heusler alloy Co2FeSi and ferroelectric-oxide Pb(Mg1/3Nb2/3)O3-PbTiO3 for an electric-field control of magnetization vectors. In this system, the non-volatile and repeatable magnetization vector switchings in remanent states are also demonstrated. This approach can lead to a new solution to the reduction in the write power in spintronic memory architectures at room temperature.

    • Shumpei Fujii
    • , Takamasa Usami
    •  & Kohei Hamaya

  • Article
    | Open Access

    We formulated micromagnetic simulation models of nanocrystalline soft magnetic materials including effects of magnetostriction, and simulated motions of domain walls to clarify mechanism of energy dissipations in the nanocrystalline soft magnetic materials. The magnetostriction is nonuniformly distributed, and magnetic energy induced by external field is converted into elastic energy due to the magnetostriction. This energy consumption generates an excess loss in the nanocrystalline soft magnetic materials even there is no eddy current. The simulation results enable us to reduce the core loss in the nanocrystalline soft magnetic materials.

    • Hiroshi Tsukahara
    • , Hiroshi Imamura
    •  & Kanta Ono

  • Article
    | Open Access

    Single Sn vacancies are dominant in slow solidification speed, while multivacancies are dominant in high solidification speed SnSe crystals. The multivacancies also provide hole carrier to the crystal and are major p-type sources in high solidification speed SnSe crystals especially in polycrystalline SnSe.

    • Van Quang Nguyen
    • , Thi Ly Trinh
    •  & Sunglae Cho

  • Article
    | Open Access

    Two-dimensional distorted orthorhombic GeS microribbons has been synthesized applying vapor-liquid-solid and vapor-solid mechanism-based chemical vapor transport. Polarized Raman and photoluminescence characterizations show the significantly angle-dependent intensity and anisotropic optical properties. Additionally, we probed the anisotropic electric properties by fabricating back-gate cross-shaped field effect transistors. In-plane direct current measurement demonstrated the charge carrier transport anisotropy and its anisotropic current ratio can be linearly adjusted by changing the gate voltage under dark and illumination conditions.

    • Zhangfu Chen
    • , Woohyun Hwang
    •  & Heon-Jin Choi

  • Article
    | Open Access

    A novel technique is demonstrated for the fabrication of individually addressable, high-density, flexible pressure sensor arrays composed of 1D ZnO nanotubes on graphene. The individually addressable pixel matrix was fabricated by arranging the top and bottom electrodes of the sensors in a crossbar configuration. A high spatial resolution of 1058 dpi was achieved for a Schottky diode-based force/pressure sensor composed of piezoelectric ZnO nanotubes on a flexible substrate.

    • Junbeom Park
    • , Ramesh Ghosh
    •  & Gyu-Chul Yi

  • Review Article
    | Open Access

    This review highlights the recent advances in fluorescence microscopic visualization of synthetic hydrogels, bio-macromolecular hydrogels, organohydrogels, and supramolecular hydrogels. Topics related to the structural changes of hydrogels, hydrogel mechanics, and super-resolution imaging of hydrogels based on fluorescence microscopy are introduced. The design concepts, imaging mechanisms, and potential applications of the novel fluorescence visualization strategies are discussed in detail. Finally, our opinions on the major challenges of current research, possible solutions, and future directions are shared.

    • Jinpan Zhong
    • , Tianyi Zhao
    •  & Mingjie Liu

  • Article
    | Open Access

    A mechanically percolated network of 2D gold nanosheets embedded within a PDMS elastomer enables the realization of elastomeric electrodes with superior mechanical sustainability and high electrical conductivity. Owing to such highly durable elastomeric electrodes facilitate the development of elastomeric electronics, including transistors, inverters, NOR, and NAND, which is expected to broaden the scope of soft electronic applications.

    • Seojun Heo
    • , Seongsik Jeong
    •  & Hae-Jin Kim

  • Article
    | Open Access

    The β-cell microcapsules prepared by the microfluidic electrospray method were transplanted into the omentum pouch of mice for intelligent release of insulin to treat diabetes. Studies have shown that microcapsules can encapsulate cells while allowing nutrients and metabolites to enter and exit. This ability helps protect cells, improve cell activity, and reduce inflammation. In addition, the β-cell microcapsules can intelligently release insulin. The constructed living cell biosystem was further demonstrated its potential as artificial islets to be transplanted into diabetic mice omentum pouch to control blood glucose levels and thus treat diabetes of mice.

    • Xiaoyu Liu
    • , Yunru Yu
    •  & Ling Li

  • Article
    | Open Access

    We report that recently synthesized NaZnBi is a new dual topological insulator, with \({\Bbb Z}_2\) indices \((\nu _0;\nu _1\nu _2\nu _3) = (1;000)\) and odd mirror Chern numbers ±1, based on the first-principles calculations. NaZnBi, which crystallizes in a tetragonal structure with the P4/nmm space group, consists of ZnBi layers and embedded Na atoms. The (100) surface electronic structure exhibits the gapless surface states, which connect the valence and conduction bulk bands. These gapless surface states form the topological Dirac point at the Brillouin zone center \(\overline{\Gamma}\). This characteristic clearly shows the topological insulating phase in NaZnBi. Moreover, by applying an external magnetic field in various directions, we verify that the topological Dirac point at \(\overline {\Gamma}\) is protected by the time-reversal and mirror symmetries, and confirm that NaZnBi belongs to the class of dual topological insulators.

    • Hyunggeun Lee
    • , Yoon-Gu Kang
    •  & Kee Joo Chang

  • Article
    | Open Access

    The “molecular knitting method” improves toughness and Young’s modulus. We prepared dual cross-network (DC) elastomers with a knitting structure and single movable cross-network elastomers with penetrating polymers (SCP elastomers) by swelling the single movable cross-network (SC) elastomers in liquid monomers. The DC elastomers showed a high toughness and a high Young’s modulus. SAXS indicated that the DC elastomers exhibited heterogeneity at the nanoscale. The DC elastomers showed a significantly broader relaxation time distribution than the SC and SCP elastomers. Thus, the nanoscale heterogeneity and broader relaxation time distribution were important to increase toughness.

    • Yusaku Kawai
    • , Junsu Park
    •  & Yoshinori Takashima

  • Article
    | Open Access

    Despite extensive previous research, the suppression in phonon conduction at the nanoscale still calls into questions on the interaction of phonons with various sources of boundary scatterings. In this work, a combination of Boltzmann transport model and the experiments finds that the bridges contribute to phonon mean free paths proportional to its volume fraction despite its negligible contribution to net heat flux. A statistical analysis of boundary scattering reveals that transport characteristics of phonon evolves from Brownian motion to Lévy walk due to phonons trapped within the bridges.

    • Yongjoon Kim
    • , Takashi Kodama
    •  & Woosung Park

  • Article
    | Open Access

    For the emergent colossal, reversible barocaloric effect in organic–inorganic perovskite hybrids (CH3–(CH2)n−1–NH3)2MnCl4 (n = 9, 10), we successfully grew a single crystal, and the underlying mechanism was determined by high-resolution SC-XRD, IR spectroscopy and DFT calculations. The drastic transformation of organic chains confined to the metallic frame from ordered rigidity to disordered flexibility is responsible for the large phase-transition entropy, which is comparable to the melting entropy of organic chains. The result provides new insights into designing novel barocaloric materials by utilizing the disordering of organic chains of organic–inorganic hybrid materials.

    • Yihong Gao
    • , Hongxiong Liu
    •  & Baogen Shen

  • Article
    | Open Access

    In this work, we systematically study heat conduction in SiC nanostructures, including nanomembranes, nanowires, and phononic crystals. Our measurements show that the thermal conductivity of nanostructures is several times lower than that in bulk and the values scale proportionally to the narrowest dimension of the structures. Additionally, we probed phonon mean free path and coherent heat conduction in these nanostructures. Our theoretical model links the observed suppression of heat conduction with the surface phonon scattering, which limits the phonon mean free path and thus reduces the thermal conductivity.

    • Roman Anufriev
    • , Yunhui Wu
    •  & Masahiro Nomura

  • Article
    | Open Access

    (Left, above) Schematic diagram describing the process of the Au implantation into the Dirac semimetal (DSM) Bi0.96Sb0.04. (Left, below) Positive longitudinal magnetic resistance (LMR) is observed in the crystal without ion implantation, but negative LMR behavior becomes apparent for ϕG ≥ 3.2 × 1016 Au cm−2 (≡ ϕC, critical implant fluence), and reaches a maximum for ϕG = 8.0 × 1016 Au cm−2. (Middle) Quantum oscillation parameters for the β Fermi pockets showing abrupt changes near ϕC, typical of phase transition. No such behavior is observed for the α Fermi pockets. (Right) A drastic change in the Raman spectra is observed for ϕG ≥ ϕC. In particular, a new peak appears at 85.7 cm−1, between the well-known Raman modes, suggesting that the inversion symmetry breaking in the crystal occurred for ϕG ≥ ϕC, resulting in the transition of the DSM to a Weyl semimetal.

    • Won Jun Lee
    • , Yusuff Adeyemi Salawu
    •  & Suk-Ho Choi

  • Article
    | Open Access

    A rare-earth intermetallic La-Ce-Fe-Si-H has been directly measured to cool 8 K when it is under a 1 kbar pressure. This barocaloric strength significantly outperforms those in previously reported phase-transitioned alloys. A multifield-dependent neutron diffraction has revealed that the large isotropic transition volume change for La-Ce-Fe-Si-H plays a crucial role in exploring the giant barocaloric effect.

    • Yanfeng Liu
    • , Xinqi Zheng
    •  & Jian Liu

Browse narrower subjects

Browse Physical sciences across other nature.com journals