https://scholar.dgist.ac.kr/handle/20.500.11750/27 2026-11-05T04:48:23Z https://scholar.dgist.ac.kr/handle/20.500.11750/61096 Title: Neutron diffraction evidence for common axial-dominant antiferromagnetic order in Fe0.7A0.3Sn (A = Co, Ni) Author(s): Park, Jaemun; Cho, Beopgil; Rhee, Taeseong; Lee, Jungmin; Kim, Jaewook; Park, Keeseong Abstract: Pristine FeSn is a kagome antiferromagnet whose ordered moments lie predominantly in the basal plane, whereas Co and Ni substitution at the Fe site has been suggested to reorient the Neel vector toward the c-axis. While the magnetic structure of Co-substituted FeSn has been investigated directly, that of Ni-substituted FeSn has remained unresolved. Here, we use neutron powder diffraction to determine the magnetic structures of polycrystalline Fe0.7Co0.3Sn and Fe0.7Ni0.3Sn. In both compounds, the absence of magnetic intensity at (0 0 1/2), together with the emergence of magnetic Bragg peaks at (1 0 1/2) and (2 0 1/2), supports predominantly axial antiferromagnetic order. Temperature-dependent diffraction further reveals subtle anomalies in the lattice parameters near the onset of magnetic intensity, suggesting a weak magnetoelastic response. Rietveld refinements at 4 K yield ordered moments of 1.26(2) mu B/(Fe, Co) and 1.12(7) mu B/(Fe, Ni) for Fe0.7Co0.3Sn and Fe0.7Ni0.3Sn, respectively, indicating suppressed long-range magnetic order relative to pristine FeSn. These results directly demonstrate that Ni substitution, like Co substitution, stabilizes a closely similar axial-dominant antiferromagnetic state in FeSn, accompanied by reduced ordered moments and suppressed ordering temperatures. 2026-09-30T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/61077 Title: MOF and MXene-derived atom-level catalysts (Fe, co and Ni): Trends, breakthroughs, and challenges in water splitting Author(s): Dhanasekaran, Thangavelu; Kumar, Ponnaiah Sathish; Kim, Young-Ki; Jeyaprabha, Balasubramanian; Lee, Sungwon; Kim, Kibum Abstract: Developing efficient and cost-effective catalysts for industrial-scale hydrogen (H2) and oxygen (O2) production is crucial for the clean energy transition. Atomically dispersed single-atom catalysts (AD SACs) (e.g., iron (Fe), cobalt (Co), and nickel (Ni)) without precious metals are particularly promising, offering 100% atomic utilization and optimum catalytic efficiency. Nonetheless, key challenges remain, including the suppression of atom aggregation, the optimization of support structures, and the maintenance of stability. Moreover, industrial catalysis demonstrates that active components with suitable supports are critical, and catalytic efficacy often increases as the size of the active components decreases, opening new frontiers in catalyst design. Thus, metal-organic frameworks (MOFs) and MXenes have emerged as effective anchoring matrices, enabling modulation of electronic structures, rapid charge transfer, and enhanced stabilization of single metal atoms. This review highlights recent progress in the development of AD SACs anchored on MOFs and MXenes, emphasizing the fundamental parameters governing hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performance. Furthermore, we integrate theoretical insights from Density Functional Theory (DFT) with advanced operando and in-situ characterization techniques to provide a comprehensive understanding of the mechanistic origins governing HER/OER activity. We anticipate that these insights will contribute to improving water-splitting efficiency and sustainability, which are vital for advancing the clean energy revolution. Finally, this review outlines future directions for the development of high-efficiency, cost-effective MXene-and MOF-based SAC catalysts, underscoring their potential in clean energy production. 2026-08-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/61075 Title: Metal-Complex-Functionalized Terpolymer Donors Enabling Efficient Solar Cells via Enhanced Dielectric Constant and Minimized Triplet Exciton Loss Author(s): Wang, Xiaoping; Cho, Yongjoon; Huang, Bin; Fang, Yu; Chen, Dong; Li, Liqing; Liu, Jin-Biao; Chen, Shanshan; Liu, Kunming; Chen, Yiwang Abstract: The dielectric constant (epsilon r) critically influences exciton generation and subsequent dissociation into free charges, playing a pivotal role in the performance of polymer solar cells (PSCs). However, the intrinsically low epsilon r of conventional polymer donors leads to strong Coulombic interactions and significant energy loss (E loss). Herein, we address this challenge through a dielectric engineering strategy by incorporating zinc porphyrin units into the matrix polymer donor D18, resulting in a series of terpolymers D18-Px (x = 5, 10, 15). The introduction of the zinc-porphyrin-based third component in the terpolymer donors significantly enhanced epsilon r and promoted favorable molecular aggregation. When blended with L8-BO, the D18-P5:L8-BO blend film demonstrated improved miscibility, efficient charge extraction and transport, and critically minimized non-radiative energy loss to 0.212 eV. Consequently, it achieved a record power conversion efficiency (PCE) of 20.27% for metalated complex-based PSCs. This work showcases a facile and effective approach for designing high-efficiency polymer donors by strategically increasing the dielectric constant and minimizing non-radiative losses. 2026-06-30T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/61064 Title: Superconductivity proximate to non-Abelian fractional spin Hall insulator in twisted bilayer MoTe2 Author(s): Ahn, Cheong-Eung; Seo, Donghae; Lee, Gyeoul; Kim, Youngwook; Cho, Gil Young Abstract: Twisted bilayer MoTe2 near two-degree twists has emerged as a platform for exotic correlated topological phases, including ferromagnetism and a non-Abelian fractional spin Hall insulator. Here we reveal the unexpected emergence of an intervalley superconducting phase that intervenes between these two states in the half-filled second moiré bands. Using a continuum model and exact diagonalization, we identify superconductivity through multiple signatures: negative binding energy, a dominant pair-density eigenvalue, finite superfluid stiffness, and pairing symmetry consistent with a time-reversal-symmetric nodal extended s-wave state. Remarkably, our numerical calculation suggests a continuous transition between superconductivity and the non-Abelian fractional spin Hall insulator, in which topological order and symmetry evolve simultaneously, supported by an effective field-theory description. Notably, our field-theoretic analysis indicates that superconductivity is driven by the condensation of charge-e/2 self-bosonic non-Abelian anyons, thereby providing a concrete realization of anyon superconductivity. Complementarily, when approached from the normal metallic side, superconductivity instead emerges from a Kohn–Luttinger instability enabled by the non-uniform quantum geometry of the flat moiré bands. Our results establish higher moiré bands as fertile ground for intertwined superconductivity and topological order, and point to experimentally accessible routes for realizing superconductivity in twisted bilayer MoTe2. 2026-04-30T15:00:00Z