Magnon Torque Transferred into a Magnetic Insulator through an Antiferromagnetic Insulator

Electrical spin-orbit torque (SOT) in magnetic insulators (MI) has been intensively studied due to its advantages in spin-orbitronic devices with ultralow energy consumption. However, the magnon torque in the MIs, which has the potential to further lower the energy consumption, still remains elusive. In this work, we demonstrate the efficient magnon torque transferred into an MI through an antiferromagnetic insulator. By fabricating a Pt/NiO/Tm3Fe5O12 heterostructure with different NiO thicknesses, we have systematically investigated the evolution of the transferred magnon torque. We show that the magnon torque efficiency transferred through the NiO into the MI can retain a high value (∼50%), which is comparable to the previous report for the magnon torque transferred into the metallic magnet. Our study manifests the feasibility of realizing the pure magnon-based spin-orbitronic devices with ultralow energy consumption and high efficiency.

ULTRARAM™: a low-energy, high-endurance, compound-semiconductor memory on silicon

ULTRARAM is a non-volatile memory with the potential to achieve fast, ultralow-energy electron storage in a floating gate accessed through a triple-barrier resonant tunneling heterostructure. Here we report its implementation on a Si substrate; a vital step towards cost-effective mass production. Sample growth using molecular beam epitaxy commenced with deposition of an AlSb nucleation layer to seed the growth of a GaSb buffer layer, followed by the III-V memory epilayers. Fabricated single-cell memories show clear 0/1 logic-state contrast after ≤10-ms duration program/erase pulses of ~2.5 V, a remarkably fast switching speed for 10- and 20-µm devices. Furthermore, the combination of low voltage and small device capacitance per unit area results in a switching energy that is orders of magnitude lower than dynamic random access memory and flash, for a given cell size. Extended testing of devices revealed retention in excess of 1000 years, and degradation-free endurance of over 107 program/erase cycles, surpassing very recent results for similar devices on GaAs substrates.

Ultralow Voltage FinFET- Versus TFET-Based STT-MRAM Cells for IoT Applications

Spin-transfer torque magnetic tunnel junction (STT-MTJ) based on double-barrier magnetic tunnel junction (DMTJ) has shown promising characteristics to define low-power non-volatile memories. This, along with the combination of tunnel FET (TFET) technology, could enable the design of ultralow-power/ultralow-energy STT magnetic RAMs (STT-MRAMs) for future Internet of Things (IoT) applications. This paper presents the comparison between FinFET- and TFET-based STT-MRAM bitcells operating at ultralow voltages. Our study is performed at the bitcell level by considering a DMTJ with two reference layers and exploiting either FinFET or TFET devices as cell selectors. Although ultralow-voltage operation occurs at the expense of reduced reading voltage sensing margins, simulations results show that TFET-based solutions are more resilient to process variations and can operate at ultralow voltages (<0.5 V), while showing energy savings of 50% and faster write switching of 60%.

Superelastic oxide micropillars enabled by surface tension–modulated 90° domain switching with excellent fatigue resistance

Superelastic materials capable of recovering large nonlinear strains are ideal for a variety of applications in morphing structures, reconfigurable systems, and robots. However, making oxide materials superelastic has been a long-standing challenge due to their intrinsic brittleness. Here, we fabricate ferroelectric BaTiO3 (BTO) micropillars that not only are superelastic but also possess excellent fatigue resistance, lasting over 1 million cycles without accumulating residual strains or noticeable variation in stress–strain curves. Phase field simulations reveal that the large recoverable strains of BTO micropillars arise from surface tension–modulated 90° domain switching and thus are size dependent, while the small energy barrier and ultralow energy dissipation are responsible for their unprecedented cyclic stability among superelastic materials. This work demonstrates a general strategy to realize superelastic and fatigue-resistant domain switching in ferroelectric oxides for many potential applications.

A High-k and Low Energy-disorder Spiro-nanopolymer Semiconductor

<p></p><p>Gridization become the rising toolbox of cross-scale chemistry that update the organic pi-conjugated polymers into nano-polymers with a nano-scale persistence length that offer the cornerstone to overcome the molecular limitation for the high-performance fourth-generation semiconductors. In this work, spiro-polygridization indeed exhibit the ultralong persistence length of ~41 nm with the extraordinary semiconducting behaviors such as a hole mobility of 3.94 × 10^-3 cm² V^-1 s^-1 and an ultralow energy disorder (<50 meV) as well as the high dielectric constant (<i>k</i> = 8.43). Gridochemistry open a way to organic intelligent multimedia facing organic intelligence.</p><p></p>

A High-k and Low Energy-disorder Spiro-nanopolymer Semiconductor

<p></p><p>Gridization become the rising toolbox of cross-scale chemistry that update the organic pi-conjugated polymers into nano-polymers with a nano-scale persistence length that offer the cornerstone to overcome the molecular limitation for the high-performance fourth-generation semiconductors. In this work, spiro-polygridization indeed exhibit the ultralong persistence length of ~41 nm with the extraordinary semiconducting behaviors such as a hole mobility of 3.94 × 10^-3 cm² V^-1 s^-1 and an ultralow energy disorder (<50 meV) as well as the high dielectric constant (<i>k</i> = 8.43). Gridochemistry open a way to organic intelligent multimedia facing organic intelligence.</p><p></p>

Robust and ultralow-energy-threshold ignition of a lean mixture by an ultrashort-pulsed laser in the filamentation regime

Laser ignition (LI) allows for precise manipulation of ignition timing and location and is promising for green combustion of automobile and rocket engines and aero-turbines under lean-fuel conditions with improved emission efficiency; however, achieving completely effective and reliable ignition is still a challenge. Here, we report the realization of igniting a lean methane/air mixture with a 100% success rate by an ultrashort femtosecond laser, which has long been regarded as an unsuitable fuel ignition source. We demonstrate that the minimum ignition energy can decrease to the sub-mJ level depending on the laser filamentation formation, and reveal that the resultant early OH radical yield significantly increases as the laser energy reaches the ignition threshold, showing a clear boundary for misfire and fire cases. Potential mechanisms for robust ultrashort LI are the filamentation-induced heating effect followed by exothermal chemical reactions, in combination with the line ignition effect along the filament. Our results pave the way toward robust and efficient ignition of lean-fuel engines by ultrashort-pulsed lasers.