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  • 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.

    • Mengli Liu
    • Wei Du
    • Xiaoli Tang
    Article Open Access
  • 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.

    • Minseok Lee
    • Sangwon Lee
    • Sungchil Yang
    Article Open Access
  • 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.

    • Kojiro Uetani
    • Keitaro Kasuya
    • Masaya Nogi
    Article Open Access
  • 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.

    • L. N. Alyabyeva
    • A. S. Prokhorov
    • B. P. Gorshunov
    Article Open Access
  • 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.

    • Zhichao Ma
    • Zhenfeng Qiang
    • Luquan Ren
    Article Open Access
  • 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.

    • Gyu Won Kim
    • Do Duc Cuong
    • Young Keun Kim
    Article Open Access
  • A large-scale and ultrafast combustion synthesis using CO2 as feedstock is demonstrated for the fabrication of nitrogen-enriched graphene frameworks (NGF) with high electrical conductivity, which delivers an upgraded kinetics due to the enhanced ion diffusion and electron transport. Lithium-ion capacitors based on NGF as both cathode and anode exhibit a high gravimetric energy density of 151 Wh kg−1 and power output of 49 kW kg−1. This study reveals an effective pathway to achieve synergistic kinetics in electrode materials for high-performance electrochemical energy storage.

    • Chen Li
    • Xiong Zhang
    • Yanwei Ma
    Article Open Access
  • Facile modification of a porous superhydrophobic polytetrafluoroethylene foam produced suitable surface structures to enable fluid slip flow and resist protein fouling. Its monolithic nature offered abrasion durability, while its porosity allowed pressurized air to be supplied to resist fluid impalement and to replenish the air plastron lost to the fluid. Active pore pressure control could resist high fluid pressures and turbulent flow conditions across a wide range of applied pressures. The pneumatically stabilized material yielded large drag reductions even with protein fouling. Coupled with its high hemocompatibility, this easily fabricated material can be viable for incorporation into blood-contacting medical devices.

    • Jennifer Marlena
    • Justin Kok Soon Tan
    • Choon Hwai Yap
    Article Open Access
  • A novel technique is demonstrated for the fabrication of flexible and highly sensitive 1D piezoelectric pressure sensors containing ZnO nanotube arrays grown on 2D graphene layers. Due to the morphology-controlled tunable sensitivity, ultra-small size, and capability of detecting extremely low pressures, the sensors are able to efficiently detect human breath and pulse.

    • Jun Beom Park
    • Minho S. Song
    • Gyu-Chul Yi
    Article Open Access
  • The significance of our results is related to “the quantum breakdown of superconductivity (QBS) and the role of superconducting islands in disordered superconducting systems”. Study on the QBS uses a reverse, comprehensive approach to the appearance of superconductivity, which is of utmost importance not only to understanding the superconducting phase but also to practical applications of superconductors. However, the mechanism underlying the transition to the nonzero resistive state deep in the superconducting state is still under debate. In this work, we have successfully achieved the field-induced QBS in disordred MgB2 thin films via a unique technique of low-energy ion irradiation.

    • Soon-Gil Jung
    • Jung Min Lee
    • Tuson Park
    Article Open Access
  • Experimental descriptions of Aβ oligomers (oli-Aβs) assembled on surfaces as compared with Aβ monomers (mono-Aβs) are crucial to understanding changes in chemical reactivity. Here, we fabricated Aβ molecular junctions between linker molecular layered electrodes using different Aβ segments and report that electron transport pathways changed from asymmetric hopping across monomeric Aβ junctions to symmetric tunneling across oligomeric Aβ junctions.

    • Sohyeon Seo
    • Jinju Lee
    • Hyoyoung Lee
    Article Open Access
  • The synchronous correspondence relationship between the optical and charge storage performances, and the synergistic intrinsic mechanism between the Al3+ ion intercalation and the surface pseudocapacitance reaction affecting the electrochromic-energy storage performance are revealed using in-situ/operando techniques.

    • Shen Wang
    • Hongbo Xu
    • Yao Li
    Article Open Access
  • We realize the introduction of crystalline chirality into transition metal dichalcogenides by intercalating polyhedra into the lattice and reveal a new type of crystalline chirality interlocked double hourglass Weyl fermion. The best candidate RhV3S6 (P6322) possesses a record wide hourglass energy window of ~380 meV, as well as strong optical circular dichroism (CD) in the infrared regime, both tunable by external strains. The chirality is originally induced by the configuration of intercalated polyhedra, then reduced by the rotational atomic displacements triggered by the intercalation, as indicated by CD calculations.

    • Pu Huang
    • Xinbo Chen
    • Xiuwen Zhang
    Article Open Access
  • We report a unique low-temperature-processed (≤100 °C) method for the scalable deposition of a tellurium nanowire network (Te-nanonet) to fabricate high-performance field-effect transistors (FETs) with stable electrical and optical properties. A maximum mobility of 4.7 cm2/Vs, an on/off current ratio of 1 × 104, and a maximum transconductance of 2.18 µS are achieved. The electrical performance of a Te-nanonet-based transistor array of 42 devices is also measured, revealing stable and uniform results. Finally, to broaden the applicability of p-type Te-nanonet-based FETs, optical measurements are demonstrated over a wide spectral range, revealing an exceptionally uniform optical performance.

    • Muhammad Naqi
    • Kyung Hwan Choi
    • Jae-Young Choi
    Article Open Access
  • A dual-responsive Co-MnO2 possessing actuation and an additional response of resistivity change in response to ultra-low visible light is introduced, with the tunable actuation triggered by a simple “activation” and Co-doping treatment. The intrinsic self-sensing, tunable and high-performing actuation in response to vis light signal is utilized to design intelligent robotics devices (e.g., self-adapting load-lifting system and auto-self-sorting finger).

    • Runni Wu
    • Kin Wa Kwan
    • Alfonso Hing Wan Ngan
    Article Open Access
  • The mechanisms involved in the damage of CVD-grown graphene (Gr) and MoS2 are investigated during a roll-based transfer process. We identify two different damage mechanisms, i.e., instability-induced damage and tensile strain-induced damage. The two mechanisms compete, depending on the thickness of the transfer medium, and induce dissimilar damage. By optimizing the thickness, we realize and demonstrate the damage-free transfer of 2D materials. The sheet resistance and mobility of transferred Gr are 235 ± 29 Ω sq–1 and 2250 cm2 V–1 s–1, respectively, with no microscopic cracks or tear-out damage.

    • Chan Kim
    • Min-Ah Yoon
    • Kwang-Seop Kim
    Article Open Access
  • Indium-free un-doped tin dioxide (SnO2) serves as a transparent conducting electrode for indoor organic photovoltaics (OPVs). SnO2 OPV systems demonstrate superior indoor performance compared with indium tin oxide (ITO)-based systems. SnO2-based OPV systems shows 14.6% efficiency under 1000 lx of LED illumination. Low-cost SnO2 can be a promising substitute for expensive ITOs in indoor OPV systems.

    • Jung-Hoon Lee
    • Young-Jun You
    • Jae Won Shim
    Article Open Access
  • By combining the MoS2 channel with the PEDOT:PSS floating layer, a new concept device is proposed. This work demonstrates optoelectronic memory operation with high mechanical endurance through a 1,000-cycle bending test, which also offers multilevel memory programming operation based on light intensity and color.

    • Seongin Hong
    • Junwoo Park
    • Sunkook Kim
    Article Open Access