The topological magnetoelectric effect (TME) in three-dimensional topological insulators (TIs), described by ΔP=(e^{2}/2h)N_{Ch}^{(2)}ΔB, serves as a condensed-matter realization of the four-dimensional quantum Hall effect (4D QHE). In dual-gate axion insulator devices, the TME-induced polarization yields a current I_{TME}∝(C_{total}/C_{S})Q_{4D-QHE}, where the signal is suppressed by the capacitance ratio C_{total}/C_{S}. Here we propose an active compensation scheme that introduces a tunable negative capacitance C_{comp}≈-C_{gate} into the gate line, effectively canceling the gate dielectric capacitance and driving C_{total}/C_{S}→1. We validate the method using a quantum anomalous Hall (QAH) device, which shares the same surface-state physics as the axion insulator but permits direct charge measurement via a single gate, recovering over 95% of the quantized charge signal from an initially half-attenuated state. This compensation method provides a robust means of resolving minute TME signals, offering a pathway toward direct measurements of the 4D QHE.

Experimental and theoretical investigation of the fragmentation reaction in the Fermi-energy domain is currently of particular importance for not only nuclear physics but also some interdisciplinary fields.In the present study,neutron-rich 14C and 16C ion beams at 27.5 MeV/nucleon were used to bombard carbon and polyethylene(CD2)n targets.Energy and angular distributions of the produced fragments were measured.Background events ori-ginating from the carbon content in(CD2)n target were efficiently excluded using an extended E-P plot method.Ex-perimental results are systematically analyzed using the HIPSE-SIMON dynamic model.The comparison reveals that,for the carbon target,the HIPSE-SIMON calculation overestimates the yields of the beam-velocity component for fragments near the projectile and also the energy phase space for fragments far away from the projectile,suggest-ing that fine tuning of the overall interaction profile adopted in the model is required.In contrast,for reactions with the deuteron target,the model calculation can reasonably reproduce the experimental data.The implication of the fragmentation mechanism on the validity of the invariant mass method,as frequently used to reconstruct the cluster-ing resonant structures in light nuclei,is also discussed.

The second 0+excited state at 7.65 MeV in 12C,known as the Hoyle state,is located near the 3-α break-up threshold and possesses a typical BEC-analog structure.This observation has triggered the intensive theoretical studies of the condensation configuration in nuclear systems,typically represented by the THSR wave function.In the mean time,the experimental investigation of the Hoyle-like states in heavier nuclei has been advanced quite slowly,due mostly to the difficulties in detecting multi-fragments in coincidence and the clarification of the reaction-decay mechanisms.We give here a review of the theoretical and experimental progresses in this field by taking into account the latest experimental outcomes for the 4-α resonance in 16O and α+2n+2n resonance in 8He.Some per-spectives are also given towards the possible BEC-like states in neutron-rich systems,which would be of particular importance in exploring the properties of the heavier neutron-rich nuclei and also the neutron stars.

LACPU, a Large Acceptance Charged particle detector array has been developed at Peking University. This system is capable of simultaneously detecting several direct reaction channels in inverse kinematics, including (d, p), (d, t), (d, 3He), (d, 4He), (d, d), (d, d '), and (d, 6Li), among others, in a single experiment. This paper reports on the solid angles, energy resolution, and particle identification capabilities of LACPU during its commissioning experiment with radioactive ion beams. Additionally, the optical potential parameters of 15C + p and 15C + d, which are essential for analyzing more complex reaction channels, have been extracted from the angular distributions of elastic scattering measured in the first experiment of LACPU.

A new inelastic excitation and cluster-decay experiment was conducted to investigate the negative-parity linear-chain structure in C-16. The helium and beryllium isotopes emitted from the highly excited states of C-16 and the recoil target deuteron were detected in coincidence. The C-16 excitation-energy spectra associated with different decay paths were reconstructed using the invariant mass method. Owing to the newly reconfigured detector setup, the detection acceptance was extended to a higher excitation-energy range, allowing a number of new resonant states to be observed beyond the previously reported pi(2)sigma(2)-bond positive-parity linear-chain band. Based on comparison with the AMD calculations for both resonance energies and relative decay widths, these newly observed states can be tentatively assigned as the 1(-), 3(-), 5(-) and 7(- )members of the negative-parity linear-chain molecular rotational band. More experimental studies are expected to directly measure the spins of these states.

Invariant-mass spectroscopy has been performed to search for possible resonance states in the loosely bound neutron-rich 15 C nucleus.By detecting alpha and 11 Be in coincidence,we reconstruct the excitation energy spectrum for 15 C.To estimate the physical background from non-resonant prompt alpha particles,we employ a recently proposed weighted event-mixing method with phenomenological reduced weighting at around the alpha-decay threshold to account for the depletion in the prompt alpha's contribution owing likely to the Coulomb final-state interactions.A new weighted mixed-event method that focuses on a robust treatment of the Coulomb effect is also proposed.Through fitting the spectrum using the background estimated with these two methods,up to two resonance state candidates are proposed.Further experiments with improved statistics and theoretical calculations are called for to confirm the se resonance states.

In this study, the process of surface morphology control was researched by combining the computation fluid dynamics (CFD) simulations and physical vapor transport (PVT) growth experiments. The results indicate the essentiality of preserving the surface structure of SiC substrate with macroscopic steps at the initial stage of the heterogeneous PVT growth. We identified an optimal range of growth temperature (Tg) and pressure to maintain the active Al vapor below a critical threshold. In the subsequent process, the pivotal factor for controlling the surface morphology of the AlN layer is identified as the supersaturation near the growing surface. Excessive supersaturation leads to a transition from a 2D to a 3D growth mode, resulting in a shift from a smooth to a rough surface morphology. An appropriate level of supersaturation can be achieved by carefully controlling the Tg, striking a balance between high surface quality and growth rate. Herein, we proposed a two-step PVT method for cultivating high-surface-quality AlN crystals on SiC substrates. At the first stage, the Tg is maintained below a threshold corresponding to the critical Al vapor pressure to preserve the surface structure until the SiC surface is completely covered by AlN. Then, Tg is elevated to near transition temperature (Ttran) to continue AlN single crystal growth at a proper rate for a long time, where Ttran is defined as the growth temperature at which the transition of the dominant mode from step growth to 3D growth happens. Two-inch-diameter AlN single crystals of thicknesses of nearly 1 mm with a smooth and lustrous surface have been obtained on SiC substrate by the two-step method.

近期在中国原子能科学研究院北京串列加速器核物理国家实验室开展的 16O + 12C 非弹散射实验，给出了 16O 中存在 4-𝛼 玻色凝聚状态的新证据。实验采用多套双面硅微条带电粒子望远镜，首次在 16O 衰变中实现了 4 个 𝛼 粒子的准确识别 (Particle Identification, PID) 和符合测量。在此基础上获得了高分辨的反应 𝑄 值谱并重建了清晰的 4-𝛼 共振态。其中在阈值附近观察到 4 个高显著度 (大部分高于 5𝜎) 的共振态，它们按照12C(Hoyle state) + 𝛼 的特征模式衰变，与理论预言的类 Hoyle-BEC 结构及其转动带特征相一致。本观测结果将推动进一步的理论研究，实验上也需要对上述共振态做更多物理量的观测。

A digital data-acquisition system based on XIA LLC products was used in a complex nuclear reaction experiment using radioactive ion beams. A flexible trigger system based on a field-programmable gate array (FPGA) parametrization was developed to adapt to different experimental sizes. A user-friendly interface was implemented, which allows converting script language expressions into FPGA internal control parameters. The proposed digital system can be combined with a conventional analog data acquisition system to provide more flexibility. The performance of the combined system was verified using experimental data.

The SnO2 electron transport layer (ETL) has been recognized as one of the most effective protocols for achieving high-efficiency perovskite solar cells (PSCs). To date, most research has primarily focused on the modification of the upper surface of SnO2 ETL films. The lower surface of the SnO2 film, which directly influences the film formation of solution-processed SnO2, is equally important but receives relatively less attention. Herein, we present a synergetic optimization approach involving the deposition of aluminum oxide (AlOx) via atomic layer deposition (ALD) as a buffer layer and the incorporation of rubidium acetate (RbAc) as an upper surface passivation additive. This process leads to a conformal coating of SnO2 nanoparticles, improved electrical performance, and higher-quality perovskite crystals. As a result, with this composite ETL film, the power conversion efficiency (PCE) reached 22.41 from 20.77%. Further modification with p-butyl iodide (BAI) on the perovskite upper surface increased the champion PCE to 23.32%, with a voltage loss of 0.41 V, ranking among the lowest values for the triple-cation mixed-halide perovskite absorber (1.58 eV). Importantly, the perovskite solar cells remained 87.30% of its initial performance after 14 days of aging and exhibited photostability under long-term UV (254 nm) illumination.

Correction for 'High-performance p-i-n perovskite photodetectors and image sensors with long-term operational stability enabled by a corrosion-resistant titanium nitride back electrode' by Tian Sun et al., Nanoscale, 2023, 15, 7803-7811, https://doi.org/10.1039/D3NR00410D.

Two-dimensional (2D) magnetic semiconductors offer an intriguing platform for investigating magneto-optoelectronic properties and hold immense potential in developing prospective devices when they are combined with valley electronic materials like 2D transition-metal dichalcogenides. Herein, we report various magneto-optoelectronic response features of the vertical hBN-FLG-CrI3-WSe2-FLG-hBN van der Waals heterostructure. Through a sensible layout and exquisite manipulation, an hBN-FLG-CrI3-FLG-hBN heterostructure was also fabricated on identical CrI3 and FLGs for better comparison. Our results show that the WSe2-CrI3 heterostructure, acting as a p-n heterojunction, has advantageous capability in light detection, especially in self-powered light helicity detecting. In the WSe2-CrI3 heterojunction, the absolute value of photocurrent I-PH exhibits obvious asymmetry with respect to the bias V, with the I-PH of reversely biased WSe2-CrI3 p-n heterojunction being larger. When the CrI3 is fully spin-polarized under a 3 T magnetic field, the reversely biased WSe2-CrI3 heterojunction exhibits advantageous capability in light helicity detecting. Both the short-circuit currents I-SC and I-PH show one-cycle fluctuation behaviors when the quarter-wave plate rotates 180 degrees, and the corresponding photoresponsivity helicities can be as high as 18.0% and 20.1%, respectively. We attribute the spin-enhanced photovoltaic effect in the WSe2-CrI3 heterojunction and its contribution to circularly polarized light detection to the coordination function of the spin-filter CrI3, the valley electronic monolayer WSe2, and the spin-dependent charge transfer between them. Our work helps us understand the interplay between the magnetic and optoelectronic properties of WSe2-CrI3 heterojunctions and promotes the developing progress of prospective 2D spin optoelectronic devices.

Increasing the open-circuit voltage (V (oc)) stands as a critical strategy for further improvingthe efficiencyof organic-inorganic halide perovskite solar cells (PSCs).Lewis basic polymers, such as polymethyl methacrylate (PMMA), areconsidered as an effective approach to reduce the nonradiative recombinationat the perovskite surface and protect the photoactive layer againstmoisture. However, the insulating nature of PMMA inherently leadsto increased series resistance in PSCs. Here, we propose a multifunctionalpassivation layer (FG-PMMA) composed of fluorinated graphene(FG) and PMMA, offering high conductivity, a good passivation effect,and excellent hole transportation capabilities. The introduction ofFG not only reduces the resistance of the PMMA layer but also improvesits hydrophobicity. More importantly, we found that fluoride, whichacts as a p-type dopant in graphene, can further reduce the nonradiativerecombination centers by forming PbF2 with uncoordinatedPb(0) at the perovskite/hole transport layer interface. Asa result, the introduction of FG-PMMA significantly enhancesthe photovoltaic performance, with a record-high open-circuit voltage(V (oc)) of 1.247 V and an average powerconversion efficiency of 22.91%, higher than those of PMMA-based devices(20.75%, 1.210 V), as well as increasing the device's moisturestability, with over 90% of the initial efficiency maintained after1200 h of aging at room temperature and a relative humidity of 35%.

In this study, we constructed two annular detector arrays comprising 24 wedge-shaped CsI(Tl) crystals, and tested them using an α source and radioactive beams of ^14-16 C on a CD _2 target. We compared the properties of a CsI(Tl) crystal encapsulated with various reflectors, revealing that using the 80- m-thick ESR film to pack the CsI(Tl) crystal yielded the largest light output with the smallest non-uniformity in light output ( Δ LO). For the 24 CsI(Tl) detectors with the 80- m-thick ESR films, the average energy resolution improved as the average light output increased; however, it deteriorated as the Δ LO value increased. To form two annular Si-CsI(Tl) telescopes for identifying the light-charged particles, the Δ LO value and energy resolution of each CsI(Tl) detector were maintained under 20 ^14-16 C + d. The results demonstrated that the Z = 1 and Z = 2 charged particles were adequately discriminated by the telescopes using the standard Δ E -E method.

A transfer reaction and cluster-decay experiment, C( O, Mg alpha+ Ne)alpha, was performed at a beam 12 16 24 ? 20 energy of 96 MeV. Both recoil and decay alpha particles were detected in coincidence, allowing us to deduce the energy momentum of a Ne fragment. A number of resonant states of Mg were reconstructed up to an excitation energy 20 24 of approximately 30 MeV. Owing to the experimentally achieved excellent resolutions of the Q-value and excitation energy spectra, the relative decay widths for each resonant state in Mg to various final states of Ne were extrac24 20 ted, along with the total decay width. The obtained results provide good testing ground for theoretical descriptions of multiple clustering configurations in 24Mg.

Despite the impressive developments in perovskite optoelectronic devices, their long-term stability remains a major challenge. Chemical reactions and ion exchange at the metal/perovskite contact interface are two significant factors that lead to the failure of perovskite devices. To address this issue, a titanium nitride (TiN) layer is introduced as a robust corrosion-resistant coating between perovskite films and metal electrodes. By introducing TiN layer, a perovskite photodiode with dark current down to 3.25 × 10-11 A cm-2 is realized. Consequently, the TiN-based perovskite photodiode shows a specific detectivity of 1.21 × 1014 cm W-1 Hz1/2, which is approximately two orders of magnitude higher than that of the control device without a TiN layer. Under continuous illumination of a 520 nm green light for 576 000 cycles, the responsivity of the TiN-based photodetector remains at 94.27% of its initial value. The TiN-based photodetector exhibits superior stability under thermal stress. After aging at 85 °C for 572 h, the TiN-based photodetector retains 72% of its initial responsivity. Using the TiN-based photodiode, a perovskite image sensor containing 64 × 64 pixelated perovskite photodiodes is constructed over an amorphous silicon thin-film transistor (TFT) backplane. The perovskite image sensor exhibits real-time imaging capability and long-term stability for over 6 months. This study highlights the importance of using metallic nitrides to achieve high-performance and air-stable perovskite devices for optoelectronic applications.

The shape and internal structure of an atomic nucleus can change significantly with increasing excitation energy, angular momentum, or isospin asymmetry. As an example of this structural evolution, linear-chain configurations in carbon or heavier isotopes have been predicted for decades. Recent studies have found non-stability of this structure in 12 C while evidenced its appearance in 16 C. It is then necessary to investigate the linear-chain molecular structures in 14 C to clarify the exact location on the nuclear chart where this structure begins to emerge, and thus to benchmark theoretical models. Here we show a cluster-decay experiment for 14 C with all final particles coincidentally detected, allowing a high Q -value resolution, and thus a clear decay-path selection. Unambiguous spin-parity analyses are conducted, strongly evidencing the emergence of the π -bond linear-chain molecular rotational band in 14 C. The present results encourage further studies on even longer chain configurations in heavier neutron-rich nuclei.

An experiment of 12C(16O,16O → 4α)12C was performed at a beam energy of 96 MeV. A large number of 4-α events were recorded in coincidence and with full particle identification (PID). This was made possible by employing a series of silicon-strip-based telescopes that provided excellent position and energy resolutions. Four narrow resonances just above the 15.1 MeV state were firmly identified in the α + 12C(7.65 MeV; Hoyle state) decay channel. Combined with the theoretical predictions, these resonant states provide new evidence for the predicted possible Hoyle-like structure in 16O above the 4-α separation threshold. Some very high-lying 4-α resonant states have also been observed and need to be further investigated.

A Li-6(O-16,Ne-19*)H-3 multi-nucleon transfer-reaction experiment was performed to populate the highly excited states in Ne. The subsequent decay particles, He-4 or protons from the Ne-19 resonant states, were detected in coincidence with the recoil H-3. The excitation-energy spectra of( 19)Ne were reconstructed using the detected proton or He and the deduced F-18 or (15O) data, respectively. A broad resonance at about 7.85 MeV (1/2(+)) was observed, with partial decay widths different from the previously reported values, which may have a significant impact on the destruction of F-18 in astrophysical processes. Several resonances up to very high excitation energies have been identified with a large alpha-clustering strength, which confirm the formation of the cluster structure with a one-hole configuration in light nuclei and encourage further systematic studies of the cluster structure in Ne-19.

We have constructed a collinear laser spectroscopy (CLS) system installed at the Beijing Radioactive Ion-beam Facility (BRIF), aiming to investigate the nuclear properties of unstable nuclei. The first on-line commissioning experiment of this system was performed using the continuous stable (39K) and unstable (38K) ion beams produced by impinging a 100-MeV proton beam on a CaO target. Hyperfine structure spectra of these two isotopes are reasonably reproduced, and the extracted magnetic dipole hyperfine parameters and isotope shift agree with the literature values. The on-line experiment demonstrates the overall functioning of this CLS system, opening new opportunities for laser spectroscopy measurement of unstable isotopes at BRIF and other radioactive ion beam facilities in China.