Advanced Physics Research最新文献

The thermal diode is a growing technology and is important for active thermal flow control. Since the theoretical designing of thermal diode in 2004, various kinds of solid-state thermal diodes have been theoretically and experimentally investigated. Here, thermal rectification in bulk-size superconductor–normal metal junctions is reported. High-purity (5N) wires of Pb and Al are soldered, and the thermal conductivity (κ) of the junctions is measured in two different directions of the heat flow, forward (κ_F) and reverse (κ_R) directions. Thermal rectification ratio (κ_F / κ_R) of 1.75 is obtained at T ∼ 5.2 K with H = 400 Oe. The merit of the Pb–Al junction is a large difference of κ in the order of several hundred W m⁻¹ K⁻¹ and magneto-tunability of the working temperature.

High-precision dynamic manipulation of 3D acoustic fields is a challenge in acoustics, crucial for applications from high-resolution imaging to targeted therapy. Conventional phased arrays (PAs), while inherently dynamic, are constrained by the size and number of piezo-elements, which imposes a trade-off among imaging resolution, aperture size, and system complexity due to the Nyquist sampling theorem. Acoustic lenses, by contrast, can provide subwavelength resolution but are intrinsically static. To reconcile these problems, here, a proposal is made to employ a steerable-plane-wave-excited meta-lens (SPWL) to combine plane-wave steering and wavefront reshaping. In SPWL, an acoustic meta-lens performs the intricate wavefront engineering, while a sparse PA is employed for flexible plane-wave steering. The strategy circumvents the Nyquist sampling criterion, thereby mitigating severe spatial aliasing which is typically associated with sparse arrays and enabling a low-cost system to achieve subwavelength focus scanning across both near and far fields. Its versatility is further demonstrated for spatial scanning of structured acoustic beams, including dual-spot focusing and vortex. Uniting the high performance, tunability and reduced complexity, the proposed SPWL system paves a transformative route toward advanced ultrasonic devices for biomedical applications.

A Protective Barrier for Heterostructures

A transparent titania capping layer protects graphene/cobalt heterostructures from oxidation while preserving interfacial magnetism. These findings highlight the achievement of air-stable graphene/metal interfaces, opening opportunities for studying related systems and enabling durable, high-performance devices. For more details see Research Article e00066 by Carlo Alberto Brondin, Matteo Jugovac and co-workers.

Scintillating crystals play a critical role in nuclear energy and radiation detection applications, such as nuclear batteries and radiation dose detectors. Both applications urgently require scintillation crystals with high radioluminescence efficiency. In this work, the Bridgman-grown 1-inch Cs₃Cu₂I₅: In single crystals demonstrate the capability of realizing a high-output-power nuclear battery and ultrabroad dynamic range radiation dose monitoring. The 1-inch Cs₃Cu₂I₅: In single crystal has a high photoluminescence quantum yield of 92%, and a high light yield of 32 000 photons MeV⁻¹ under gamma-ray irradiation. The inch-sized Cs₃Cu₂I₅: In-based nuclear battery can achieve a high output power of 1.45 µW, superior to that of most radioluminescent-type nuclear batteries based on commercial and emerging scintillators. The Cs₃Cu₂I₅: In-based dosimeter can realize an exceptional dynamic response range of 7.2–46 300 mGy h⁻¹ with a linear correlation coefficient R² of 0.9999. This work proves the effectiveness of bulk Cs₃Cu₂I₅: In single crystals, acting as the key component of scintillators toward nuclear battery and radiation dose monitor.

A two-time extension of the past–future quantum state formalism is introduced, where a quantum system is represented by a forward-evolving density matrix ρ(t) and a backward-evolving effect matrix σ(t′) defined at generally distinct times t ≠ t′. The separation Δt = t′ − t provides additional freedom for modeling time-symmetric quantum dynamics. Within this framework, two-time weak values are defined and their implications are investigated for the Berry phase in a spin system, the spontaneous decay, and dwell time in a model of a two-level atom coupled to an atomic ensemble. The Berry phase emerges as a tunable quantity in this approach, with its value controlled by Δt, extending beyond conventional adiabatic constraints. It is further showed that the decay dynamics are strongly modulated by Δt, enabling either suppression or enhancement of the effective decay rate. Additionally, a closed-form expression is derived for the dwell time under weak measurement. These findings highlight the conceptual utility of the two-time formalism for exploring time-resolved quantum processes and suggest potential relevance for future studies in areas such as quantum control, feedback, and coherence preservation in open systems.

Here, optoelectronic synaptic device based on thin film mesoporous titania (meso-TiO₂) is demonstrated as sensing active layer under illumination of low power laser pointers (532 nm or 632 nm), which could modulate weight change of input signal under the light-illumination and electrical-bias sequentially. Moreover, through both photonic and electronic co-modulation of input signal on the aluminum/meso-TiO₂/indium tin oxide (ITO) device array, multiple hand-writings of numerical letters of “3” and “5” by laser pointer could be identified, stored, and erased. The laser pointer drawn letter images were self-adaptively preprocessed and memorized as photosynaptic perception concept with the visual neuromorphic 28 × 28 array. Moreover, the photosynaptic devices were demonstrated to possess self-rectifying and three different meso-TiO₂ device's formats of crossbar, cap, and lateral electrode structures along with the various metal materials for top and bottom electrodes. In addition, the current–voltage (I–V) characteristics with series of photonic potentiation by lase pointer could show excitatory postsynaptic current (EPSC) behavior as well. In addition, thermal protocol of erase for the laser induced memory was examined, which could reset the adaptively perceived and memorized image under laser illumination. Accordingly, the dual modulation of photo-synaptic meso-TiO₂ array can open initial step for artificial visual platform for image acquisition and preprocessing.

The contact resistance of organic thin-film transistors (TFTs) fabricated in the inverted coplanar (bottom-gate, bottom-contact) device architecture has been predicted to depend on the thickness of the source and drain contacts. To investigate this dependence experimentally, organic TFTs with a contact thickness ranging from 6 to 50 nm are fabricated and their contact resistance is measured using the transmission line method (TLM). Gold is used as the contact metal, and the contacts are functionalized with a chemisorbed monolayer of pentafluorobenzenethiol (PFBT). As the semiconductor, the vacuum-deposited small-molecule material 2,9-diphenyl-dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (DPh-DNTT) is employed. A trend toward smaller contact resistances is observed when the contact thickness is increased from 6 to 25 nm, and the contact resistance appears to saturate at a value of ≈100 Ωcm once the contact thickness exceeds a value of ≈30 nm. For the most part, this is consistent with results from simulations presented in the literature.

Thermal Characterization for UWBG Devices

Review number e2500039 by Hassan Irshad Bhatti and Xiaohang Li highlights state-of-the-art thermal characterization techniques for ultrawide bandgap (UWBG) semiconductor devices, including Ga₂O₂, AlN, and diamond. By critically evaluating optical and electrical methods–such as thermoreflectance imaging, micro-Raman thermometry, and micro-thin film thermocouples–the study guides effective thermal metrology selection to address self-heating and reliability in next-generation power and RF electronics.