Journal of the Korean Physical Society最新文献

Two-dimensional magnetic materials offer exciting possibilities for spintronic applications due to their tunable properties and reduced dimensionality. In this study, we employ density functional theory-based first-principles calculations to investigate the strain-dependent magnetic and electronic properties of monolayer FeCl(_2). The unstrained monolayer exhibits a robust ferromagnetic ground state with half-metallic character, and the Fe(^{2+}) ions remain in a high-spin configuration across the strain range of (-5%) to (+5%), indicating no spin-crossover transition. The Curie temperature, estimated via a mean-field Heisenberg model, is approximately 16 K. Notably, magnetocrystalline anisotropy energy calculations reveal a strain-induced reorientation of the magnetic easy axis from in-plane to out-of-plane at around 4% tensile strain, providing a controllable handle for spintronic device design. Phonon dispersion and formation energy analyses confirm the dynamical and thermodynamic stability of the monolayer. These results highlight the potential of FeCl(_2) as a stable, strain-tunable platform for 2D spintronic applications. Future studies involving substrate effects, chemical doping, or heterostructure engineering may further enhance magnetic ordering and broaden the material’s applicability in low-dimensional device architectures.

Solitary wave propagation is vital structure in nonlinear science due to their stability and persistence. In this work, we explore the diverse soliton solutions and quasi-periodic structures for the Sharma–Tasso–Olver–Burgers equation. By applying the generalized Arnous method and the new modified generalized exponential rational function method, we obtain bright solitons, dark solitons, periodic waves, singular structures, and exponential-type localized solutions. The formation and propagation of these waves are captured through graphical illustration of 3D, 2D and density plots and validity of results confirmed. Additionally, we perturb the dynamical system corresponding to the studied equation and observe quasi-periodic behavior in the perturbed system using various chaos detection tools. These results have potential applications in fluid dynamics, plasma physics, nonlinear optics, and high-speed signal transmission.

We investigated magnetic moment behaviors of a frustrated antiferromagnet Ba₃CoSb₂O₉ using the field-dependent full-multiplet CoO₆ cluster model calculations with physical quantities determined from the Co L_2,3-edge X-ray absorption spectroscopy (XAS) analysis. The XAS analysis shows that the Co 3d spin–orbit coupling is essential to determine the ground state, which becomes Kramer’s doublet states, the so-called J_eff = 1/2 states, split by the spin–orbit coupling from the conventional high spin S = 3/2 ⁴T₁ (t_2g⁵e_g²) states. The calculation yields a 2.17 μ_B ground state magnetic moment consistent with the reported ~ 1.93 μ_B extrapolated from the high field M–H magnetization curve. Our field-dependent model calculations successfully well reproduce the field-dependent magnetization M(H) in the high field region (> 30 T). The spin–orbit coupling turns out to originate an anomalously large van Vleck paramagnetism well explaining the reported susceptibility.

Single-molecule analysis techniques, including single-molecule fluorescence resonance energy transfer (smFRET), super-resolution microscopy (SRM), and force spectroscopy, provide indispensable insights into molecular heterogeneity and transient dynamics. However, the quantitative power of these approaches is fundamentally limited by conventional stochastic labeling methods, which often yield heterogeneous stoichiometry, functional perturbation, and substantial spatial uncertainty due to linkage errors. To address these challenges, this review systematically examines state-of-the-art strategies for precise, site-specific fluorophore attachment. We categorize key approaches ranging from well-established chemical modifications (e.g., cysteine-maleimide) to advanced enzymatic tags (e.g., SNAP-tags, HaloTags) and genetic code expansion (GCE) coupled with bioorthogonal chemistry. Crucially, beyond a mere overview of methods, we highlight an integrative workflow that synergizes these labeling strategies with advanced computational modeling—such as structural prediction and molecular dynamics simulations—to enable rational experiment design and minimize linkage errors. We further discuss how these optimized protocols enhance labeling stoichiometry and probe photostability, thereby extending the spatiotemporal resolution of in-cell imaging. Finally, we conclude with emerging directions, focusing on orthogonal multi-site labeling schemes and next-generation fluorophores that promise high-fidelity molecular tracking under physiologically relevant conditions.

The Fe₂CuAl Heusler alloy is considered a valuable candidate for future magnetic technologies, including spintronics, sensing, and data storage, due to its adjustable magnetic characteristics. In this work, a mechanical alloying approach was employed to synthesize Fe₂CuAl powders, followed by comprehensive structural and magnetic characterization. XRD analysis confirmed the formation of a nanocrystalline Fe₂CuAl phase after 24 h of milling, accompanied by an increasing lattice parameter with milling duration, indicating solute diffusion. SEM revealed significant morphological evolution toward homogeneous and refined particles. Magnetic hysteresis measurements demonstrated a peak in coercivity at 8 h (102.4 Oe), attributed to microstructural refinement, while the saturation magnetization remained within a narrow range (95.9–104.9 emu/g). A declining trend in the Mr/Ms ratio beyond 24 h suggests an increase in structural disorder. Overall, the synthesized Fe₂CuAl alloy exhibits a stable A2-type disordered structure, demonstrates the effectiveness of mechanical alloying to fine-tune microstructure and magnetic behavior in Fe-based Heusler systems, offering insights into their optimization for magnetic device applications.

Accelerators that generate charged particle beams and boost them to the required energies have become an integral part of our daily life in various domains, ranging from materials processing and testing, medical diagnostics and therapy, and large-scale scientific discovery. This review traces the historical development of Korea’s accelerator technology, summarizes the status of domestic large-scale accelerator facilities, and outlines strategic directions for next-generation infrastructures and applications. We highlight the current challenges and future opportunities across both discovery sciences and applied sectors, including global trends and Korea’s position in the international landscape.

Radiation sensors play a crucial role in diverse fields such as medical diagnostics, environmental monitoring, and nuclear safety. However, many conventional sensors face challenges related to limited sensitivity and operational stability. In this work, we theoretically propose a high-performance γ-ray radiation sensor based on a one-dimensional porous silicon photonic crystal (1D PhC) incorporating a gallium arsenide (GaAs) defect layer and porous silicon layers infiltrated with chalcogenide glass compositions (Se₇₀S_30–xSb_x). The sensing principle is governed by monitoring the shift of the defect mode resonance within the photonic band gap as a function of γ-ray dose (0–500 kGy). Variations in the refractive index of the irradiated chalcogenide glasses were modeled using Bruggeman’s effective medium approximation and incorporated into transfer matrix method (TMM) simulations. The proposed design combines structural simplicity, cost efficiency, and superior sensing metrics, underscoring its strong potential for practical deployment in nuclear radiation detection, medical imaging, and industrial monitoring applications.

Superconducting coplanar waveguide (SCPW) resonators with high internal quality factors (Q_i) are essential for quantum information applications, but suffer severe Q_i degradation under magnetic fields due to quasiparticle generation and vortex-induced losses. We fabricated and characterized Nb, NbTi, and NbTiN SCPW resonators with varying film thicknesses under different temperatures and in-plane magnetic fields (B_||). Temperature-dependent transmission measurements agree well with Mattis–Bardeen theory, revealing kinetic inductance parameters. Comparative analysis shows that 45-nm-thick NbTi resonators maintain Q_i = 1.01 × 10⁴ at B_|| = 0.4 T, satisfying the dual requirements of high Q_i and strong field resilience. Owing to its moderate kinetic inductance and compatibility with conventional photolithography, NbTi emerges as a practical material platform for field-resilient SCPW resonators and hybrid quantum circuits operating in magnetic environments.

This work investigates a Gate-All-Around Field-Effect Transistor (GAA-FET) architecture employing an underlap configuration, with Gallium Arsenide (GaAs) as the substrate material and silicon dioxide (SiO₂) as the gate dielectric. The device is designed at the 22 nm technology node, where the introduction of underlap regions—intentional spacing between the gate and source/drain contacts offers refined control over short-channel behavior and electrostatic integrity. The proposed GaAs underlap GAA-FET structure introduces an optimized 2.5 nm underlap region validated through calibrated TCAD modeling, achieving improved short-channel control and switching efficiency compared to prior works. GaAs is selected for its high electron mobility, which enhances channel transport characteristics compared to conventional silicon-based implementations. Device modeling and electrical analysis are performed using Technology Computer-Aided Design (TCAD) tools to evaluate the impact of the underlap geometry on key performance indicators. Critical parameters, including V_th, drive current, leakage current, ON/OFF current ratio, subthreshold slope, and Drain-Induced Barrier Lowering (DIBL), are systematically analyzed. The role of fringing fields and parasitic capacitances induced by the underlap layout is also examined for their influence on switching behavior and device scaling. Simulation outcomes confirm that the proposed GaAs-based underlap GAA-FET structure offers improved electrostatic control, reduced leakage, and enhanced switching performance, positioning it as a strong candidate for future ultra-scaled, energy-efficient semiconductor technologies.

Hydrogen exposure plays a critical role in determining the surface chemistry and electrical behavior of amorphous In–Ga–Zn–O (a-IGZO) thin films, which are widely used as transparent channel materials in oxide-based electronics. In this study, we performed an in situ synchrotron-based X-ray photoelectron spectroscopy (XPS) investigation on hydrogen-exposed a-IGZO surfaces to elucidate the competing effects of hydrogen incorporation on oxygen vacancies (V_O) and metallic states. Clean a-IGZO thin films were sequentially exposed to atomic hydrogen at coverages of 3.6 × 10⁴ L and 1.1 × 10⁵ L. As the hydrogen exposure increased, the O 1s spectra revealed a systematic reduction of both the oxygen vacancy (O_V) and metal–oxide (O_M) components, while the valence band spectra exhibited a simultaneous decrease in deep subgap states (DSS) and an enhancement of metallic features near the Fermi level. The In 3d spectra further confirmed the growth of metallic indium (In⁰) species, indicating that hydrogen not only passivates oxygen vacancies, but also induces reduction of indium ions at the surface. These findings suggest that hydrogen incorporation leads to two competing processes—vacancy filling and metal-ion reduction—that together influence the electronic transport behavior of a-IGZO thin films under hydrogen-rich environments. The results provide new insight into the role of hydrogen in tuning surface electronic structures of oxide semiconductors, which is crucial for reliable device performance and long-term stability.