Observation of superconductivity, magnetism, and correlated insulating phases driven by the moiré potential in twisted graphene bilayer has opened the exciting new field of "twistronics". Even richer physics is expected if moiré superlattice could be generated on topological insulators; however, until now, experimental studies have been scarce. Here, we demonstrate topological moirés generated by adsorbing a monolayer of noble gas on a topological insulator. By angle-resolved photoemission spectroscopy, we show that the moiré potential replicates the topological surface state and affects it in a way fundamentally different from the trivial states. Replicated Dirac cones generally avoid crossings, except at the time-reversal invariant momenta that remain gapless. This creates van Hove singularities at the moiré Brillouin zone corners, providing the mechanism of enhancing correlations. Indeed, we observe a strong enhancement of the electron-phonon coupling strength that, if properly tuned, might lead to topological superconductivity and Majorana Fermions.

The electron-phonon (e-ph) coupling is crucial in explaining various ordering phenomena such as superconductivity and charge density waves (CDW) which has been invoked to explain Cooper pair formation leading to superconductivity, however, the origin of charge state mechanism is not yet fully understood. Here we study the role of e-ph coupling in understanding the interplay of the structural phase transition, CDW transition, superconducting transition, and flat electronic band dispersion in the La$_{2-x}$Sr$_{x}$CuO$_4$ ($x$ = 0.15) superconductor. We employed high-resolution temperature dependent x-ray diffraction and Raman scattering measurements in combination with first-principles calculations across the phase-transitions. We unveil the dominant role of CuO$_6$ octahedra distortion and tilting which suggests the presence of strong e-ph coupling that gradually develops high alternating CuO$_6$ octahedra rotations [in-phase (+ve) and anti-phase (-ve); $\phi$ $\approx$ 3$^{\circ}$)] which can further enhanced e-ph coupling below the structural-phase transition ($T_s$ = 150 K), leading to the symmetry-breaking. We observe that the local distortion of CuO$_6$ including tilting and phonon modes at $\cong$ 430, 360, 225, and 100 cm$^{-1}$ may associated with CDW correlations below $T_s$. Further, our theoretical calculations across the superconducting transition suggests the presence of strong hybridization of Cu 3$d$ with O 2$p$ orbitals, indicating the role of alternating CuO$_6$ octahedra tilt in the electronic structure of La$_{2-x}$Sr$_{x}$CuO$_4$. Thus, the octahedral tilt played a crucial role in the origin of the CDW phase.

Indium-doped SnTe (Sn1−xInxTe) provides a model platform for exploring the emergence of superconductivity within a topological crystalline insulator. Here, we present a systematic investigation of the structural, transport, and thermodynamic properties of high-quality single crystals with 0.0 ≤ x ≤ 0.5. All compositions up to x = 0.4 form a single-phase cubic structure, enabling a controlled study of the superconducting state. Electrical resistivity and specific heat measurements reveal a bulk, fully gapped s-wave superconducting phase whose transition temperature increases monotonically with In concentration, reaching Tc ≈ 4.7 K at x = 0.5. Analysis of the electronic specific heat and McMillan formalism shows that the electron–phonon coupling constant λel-ph systematically increases with doping, while the Debye temperature systematically decreases, resulting in the lattice softening. This behavior, together with the observed evolution of the normal-state resistivity exponent from Fermi-liquid (n ≈ 2.04) toward non-Fermi-liquid values (n ≈ 1.72), demonstrates a clear crossover from weak to strong interaction with increasing In content. These results establish Sn1−xInxTe as a tunable superconducting system in which coupling strength can be continuously controlled, offering a promising platform for future studies on the interplay between phonon-mediated superconductivity and crystalline topological band structure.

Abstract Interfacial superconductivity (IS) has been a topic of intense interest in condensed matter physics, due to its unique properties and exotic photoelectrical performance. However, there are few reports about IS systems consisting of two insulators. Here, motivated by the emergence of an insulator-metal transition in type-III heterostructures and the superconductivity in some “special” two-dimensional (2D) semiconductors via electron doping, we predict that the 2D heterostructure SnSe 2 /PtTe 2 is a model system for realizing IS by using first-principles calculations. Our results show that due to slight but crucial interlayer charge transfer, SnSe 2 /PtTe 2 turns to be a type-III heterostructure with metallic properties and shows a superconducting transition with the critical temperature ( T c ) of 3.73 K. Similar to the enhanced electron–phonon coupling (EPC) in the electron-doped SnSe 2 monolayer, the IS in the SnSe 2 /PtTe 2 heterostructure mainly originates from the metallized SnSe 2 layer. Furthermore, we find that its superconductivity is sensitive to tensile lattice strain, forming a dome-shaped superconducting phase diagram. Remarkably, at 7% biaxial tensile strain, the superconducting T c can increase more than twofold (8.80 K), resulting from softened acoustic phonons at the M point and enhanced EPC strength. Our study provides a concrete example for realizing IS in type-III heterostructures, which waits for future experimental verification.

The fundamental interplay between pressure-driven electronic transitions and anisotropic optical responses remains unresolved in layered black phosphorus (BP), particularly regarding polarization-selective signatures under compression. By deploying high-pressure angle-resolved polarized Raman spectroscopy, we systematically investigate the pressure-induced optical anisotropy characterized by the effective Raman tensor element ratio of Ag modes from bulk to atomically thin BP flakes. Under hydrostatic compression, two reversals in the Raman tensor element ratio are observed at around 1 and 2.5 GPa, closely corresponding to critical electronic transitions, including bandgap closure and enhanced electron–phonon coupling. Anisotropic dielectric calculations further demonstrate that these transitions are primarily driven by dielectric property evolution along the armchair direction. This work paves the way for pressure-designed multifunctional engineering in van der Waals materials.

Lanthanum oxide (La2O3) nanoparticles (NPs) were synthesized via a green co-precipitation method using Coleus barbatus leaf extract as a reducing and capping agent, with CTAB as a stabilizer. X-ray diffraction (XRD) confirmed a hexagonal polycrystalline structure with an average crystallite size of 16 nm, further supported by Raman spectroscopy. Calcination temperature played a critical role: at 600°C, incomplete precursor decomposition was observed, while 800°C treatments led to oxygen vacancies and peak broadening. Optimum properties were achieved at 700°C, with 73.80% oxygen content, sharp XRD peaks, and absence of secondary phases. UVvisible diffuse reflectance spectroscopy revealed bandgap narrowing from 4.6 to 4.28 eV with increasing temperature, attributed to reduced strain and improved crystallinity, and enhanced electronphonon coupling. Photoluminescence spectra (550 nm excitation) showed enhanced emission intensity at higher temperatures, indicating increased defect states and thermally assisted radiative transitions. High resolution transmission electron microscopy revealed spherical to hexagonal particles averaging 31.7 nm, while scanning electron microscopy indicated moderate agglomeration. The La2O3 NPs exhibited significant antibacterial activity and excellent H2S gas sensing performance, with 81% sensitivity and rapid response (11 s) and recovery (35 s) times, demonstrating strong potential for environmental monitoring and biomedical applications.

Energy conversion dynamics is critical for advancing next-generation photovoltaics, optoelectronics, and light-harvesting technologies. Noble metal plasmonic nanoparticles play a pivotal role as nanoscale electromagnetic confinement structures, driving photon-induced chemical reactions. In this study, we explore the effects of [Ru(bpy)3]2+ functionalization and aggregation on citrate-capped gold nanoparticles (AuNPs) of 40 and 100 nm diameters, focusing on molecule-plasmon interactions and their influence on electronic and energy dissipation properties. X-ray absorption near-edge spectroscopy (XANES) revealed that [Ru(bpy)3]2+ functionalization induces controlled aggregation without altering the oxidation state of gold. A more pronounced white-line intensity is observed in 40 nm AuNPs, consistent with greater s–p–d hybridization and a higher density of surface states, likely influenced by both nanoparticle size and aggregation. Transient absorption (TA) spectroscopy highlights faster electron–phonon relaxation dynamics in aggregated 40 nm nanoparticles, which is attributed to increased electron delocalization and more efficient coupling to the phonon bath. In contrast, 100 nm nanoparticles exhibit minimal changes due to a lower degree of aggregation. Interestingly, we observe that enhanced electron–phonon coupling in aggregated nanoparticles coincides with a slowing of electron–electron scattering. These observations suggest a competitive interplay between the two relaxation pathways, where enhanced energy transfer to the lattice in aggregated systems can suppress electronic thermalization. These findings underscore the critical role of nanoparticle size, aggregation, and molecule–surface interactions in modulating plasmonic dynamics and excited-state lifetimes and further provide valuable insights into designing tailored plasmonic systems with transformative potential for sensing, catalysis, and energy conversion.

Recently, Cu(I)-based metal halides have attracted tremendous attention owing to their remarkable photophysical properties. However, most of them can only be excited by near ultraviolet (UV) light at a wavelength (generally less than 350 nm) with a wide bandgap, which undoubtedly limits their application in solid-state lighting due to the low excitation efficiency at about 400 nm in devices. Here, we report a new zero-dimensional organic cuprous bromide of (C13H30N)2Cu5Br7 single crystals, which can be excited by visible light (390–400 nm) and give a bright yellow and broad self-trapped exciton emission band with the photoluminescence quantum yield (PLQY) of 92.3% at room temperature. The experimental and theoretical results show that the existence of Cu-Br-Cu metal bonds in a Cu5Br7 cluster package produces three components of self-trapped excitons (STE) that emit at room temperature but merge into one at 80 K. This occurs because of the anomalously enhanced electron–phonon coupling and electron–electron coupling in the coupled clusters in this system. These effects cause the excitation near visible light and emission broader at higher temperature. Additionally, their remarkable anti-water emission stability was demonstrated even after soaking in water for 6 h. Finally, a highly efficient white-light-emitting diode (WLED) based on (C13H30N)2Cu5Br7 was fabricated.

Tuning interlayer interactions offer an alternative approach to access novel electronic structure and intriguing physical properties in layered materials. Here, the emergence of a new form of superconductivity in two‐dimensional (2D) binary phosphides by strengthening the interlayer coupling with lattice compression is reported. Electrical transport measurements show strong evidence of superconductivity in InP3 with the highest critical temperature (Tc) of 9.5 K at 45.1 GPa. Raman and X‐ray diffraction (XRD) measurements indicate that the interlayer interactions are dramatically modulated under compression, along with the deformation of local In–P bipyramid structure and reduction of the interlayer distances, which eventually results in the formation of In–P bonds between neighboring In–P bipyramids and a Rm to Cmcm structural transition. First‐principles density functional theory (DFT) calculations reveal that pressure enhances the interlayer interactions, which increases the density of states (DOS) near the Fermi surface (N(EF)) and strengthens the electron–phonon coupling. Consequently, this favors the occurrence of superconductivity in compressed InP3. This study not only introduces a new superconductivity phase with enhanced electron–phonon coupling in binary phosphides, but also provides a platform for exploring the pressure effect on interlayer interactions in material systems with corrugated layered structure.

The hexagonal Mn5Si3-type compounds possess the capability to accommodate specific atoms in the interstices, thereby creating filled Mn5Si3-type structures. In Nb-based Mn5Si3-type system, interstitial atoms like carbon (C) or oxygen (O) have been identified to induce or enhance superconductivity. However, the compounds filled with nitrogen (N) are scarce, and the existence of a N-filled superconductor remains unknown. Here, we report the discovery of a novel ternary nitride superconductor, Nb5Ir3N, synthesized via incorporating N into the electride Nb5Ir3. The crystal structure of Nb5Ir3N conforms to the filled Mn5Si3-type, belonging to the P63/mcm space group (No. 193), with cell parameters a = b = 7.8398(2) Å and c = 5.1108(1) Å. Electrical resistivity and magnetic susceptibility demonstrate that Nb5Ir3N is a type-II superconductor with a T c of 8.7 K. The estimated lower and upper critical fields are 11.0 mT and 12.16 T, respectively. Moreover, specific heat measurements confirm the bulk superconductivity with enhanced electron–phonon coupling in Nb5Ir3N, as demonstrated by the normalized specific heat jump ΔC e/γT c ∼ 1.59. First-principles calculations emphasize the strong spin–orbit coupling in Nb5Ir3N.

Highly-crystallized carbon nitride (HCCN) nanosheets exhibit significant potential for advancements in the field of photoelectric conversion. However, to fully exploit their potential, a thorough understanding of the fundamental excitonic photophysical processes is crucial. Here, the temperature-dependent excitonic photoluminescence (PL) of HCCN nanosheets and amorphous polymeric carbon nitride (PCN) is investigated using steady-state and time-resolved PL spectroscopy. The exciton binding energy of HCCN is determined to be 109.26 meV, lower than that of PCN (207.39 meV), which is attributed to the ordered stacking structure of HCCN with a weaker Coulomb interaction between electrons and holes. As the temperature increases, a noticeable reduction in PL lifetime is observed on both the HCCN and PCN, which is ascribed to the thermal activation of carrier trapping by the enhanced electron–phonon coupling effect. The thermal activation energy of HCCN is determined to be 102.9 meV, close to the value of PCN, due to their same band structures. Through wavelength-dependent PL dynamics analysis, we have identified the PL emission of HCCN as deriving from the transitions: σ*–LP, π*–π, and π*–LP, where the π*–LP transition dominants the emission because of the high excited state density of the LP state. These results demonstrate the impact of high-crystallinity on the excitonic emission of HCCN materials, thereby expanding their potential applications in the field of photoelectric conversion.

Nanodiamonds that contain germanium-vacancy centers (GeV-NDs) exhibit significant potential for biomedical and quantum science applications. GeV-NDs with an average particle size of 9 nm were recently fabricated through a detonation process that enables the practical-scale production of detonation NDs (DNDs). However, the optical properties of the GeV centers in the DNDs have not been studied thoroughly. In particular, the luminescence spectrum of these GeV-DNDs had an unassigned peak at 1.98 eV. Here, we investigate the optical properties of GeV-DNDs under various conditions. Although the GeV-DNDs exhibit a zero-phonon line (ZPL) with similar excitation energy dependence and photostability to their bulk counterparts, the ZPL linewidth is broader. The 1.98 eV-peak is attributed to a composite phonon sideband peak. The unique properties of the GeV centers in these small DNDs are explained by enhanced electron–phonon coupling.

Regulating the interlayer transfer of excited charges is challenging but crucial for high-efficiency photoelectric conversion devices based on semiconductor heterojunction. In this work, the interlayer transfer and recombination of excited charges are investigated for the heterobilayers based on monolayer MoSSe and WS2 by combining density functional theory calculation with nonadiabatic molecular dynamics simulation. Our results reveal that the heterobilayers possess type-II band alignments and the interface engineering from S–Se to S–S stacking configuration reverses the spatial distribution of valence and conduction bands from MoSSe and WS2 to WS2 and MoSSe layers, respectively, which produces interlayer transfer of excited charges in opposite direction. The interface engineering also causes the delocalization of out-of-plane phonon states from the WS2 layer to both WS2 and MoSSe layers. This delocalized character in S–S configuration facilitates the simultaneous coupling of out-of-plane phonon states with the localized donor and acceptor electronic states, accelerates the motion of interface atoms, and reduces the band energy differences, which synergistically promote interlayer transfer of excited charges. As a result, the interlayer transfer of excited charges in S–S configuration is faster than that in S–Se configuration. Our investigation demonstrates that delocalizing phonon states through interface engineering can regulate electron–phonon coupling and interlayer transfer of excited charges.

Warm dense matter (WDM) represents a highly excited state that lies at the intersection of solids, plasmas, and liquids and that cannot be described by equilibrium theories. The transient nature of this state when created in a laboratory, as well as the difficulties in probing the strongly coupled interactions between the electrons and the ions, make it challenging to develop a complete understanding of matter in this regime. In this work, by exciting isolated ∼8 nm copper nanoparticles with a femtosecond laser below the ablation threshold, we create uniformly excited WDM. Using photoelectron spectroscopy, we measure the instantaneous electron temperature and extract the electron-ion coupling of the nanoparticle as it undergoes a solid-to-WDM phase transition. By comparing with state-of-the-art theories, we confirm that the superheated nanoparticles lie at the boundary between hot solids and plasmas, with associated strong electron-ion coupling. This is evidenced both by a fast energy loss of electrons to ions, and a strong modulation of the electron temperature induced by strong acoustic breathing modes that change the nanoparticle volume. This work demonstrates a new route for experimental exploration of the exotic properties of WDM.

We report on resonance Raman spectroscopy measurements with excitation photon energy down to 1.16eV on graphene, to study how low-energy carriers interact with lattice vibrations. Thanks to the excitation energy close to the Dirac point at K, we unveil a giant increase of the intensity ratio between the double-resonant 2D and 2D^{'} peaks with respect to that measured in graphite. Comparing with fully abinitio theoretical calculations, we conclude that the observation is explained by an enhanced, momentum-dependent coupling between electrons and Brillouin zone-boundary optical phonons. This finding applies to two-dimensional Dirac systems and has important consequences for the modeling of transport in graphene devices operating at room temperature.

Abstract Electron–phonon mediated superconductivity is deeply investigated in two boron based monolayer materials, namely, , a metal exhibiting the ability to superconduct, and a new metal, , presenting perfect kinetic stability. Calculations based on density functional perturbation theory combined with the maximally localized Wannier function also reveal that both materials exhibit anisotropic planar hexagonal structure like graphene. The key parameters involved in the superconductor behavior are all calculated. The electronic density in the Fermi surface is given to provide the environment for enhanced electron–phonon coupling. The longitudinal and transverse vibration modes of optical phonons mainly contribute to the electron–phonon coupling strength. Furthermore, the binding energy between the bosonic Cooper pair superfluid is quantified and determined. The critical temperature for the two materials is 20 and 10.5 K, respectively. The results obtained show the potential use of such materials for superconducting applications.

The [SbCl5]2− distortions modulate triplet STE emissions. The enhancement of high-energy triplet emission is ascribed to enhanced electron–phonon coupling, promoted intersystem crossing process, as well as restrained nonradiative transitions.

Laser power-dependent Raman spectroscopy is deployed to probe Fano interference in asymmetrically broadened Tg modes and the associated line shift in three technologically sound, meticulously characterized rare-earth sesquioxide systems. Group theoretical analysis is accompanied to introspect the Raman-active optic modes in cubic, monoclinic, and trigonal phases and identify the laser heating-induced local phase transitions. With increasing laser intensity, a regular redshift and larger negative asymmetry in the Raman peaks are detected, which is attributed to moderations in Fano scattering by enhanced electron–phonon coupling amid the focussed photoexcited electron plasma and is illustrated using a Feynman diagram. A quantitative study is thereby performed to unveil the intrinsic nature of discrete-continuum Fano resonance in the nanoparticles of interest emphasizing the high sensitivity of Raman spectra to the excitation strength that perturbs the generic vibrational features at the Brillouin zone center by influencing the interference conditions, force constant, and length of the associated bonds compelled by tensile stress. A rising trend of the charge–phonon coupling constant (λ) with laser power validates a stronger particle–quasiparticle coupling, whereas a shorter anharmonic phonon lifetime (τanh) indicates faster interactions. Using Allen's formalism, the charge density of states [N(εF)] at the Fermi level per spin and molecule is calculated, which pertains to a negative regression dependence in the λN(εF)−τanh dynamics.

Understanding the coupling between electrons and phonons in iron chalcogenides FeTeSe has remained a critical but arduous project in recent decades. The direct observation of the electron–phonon coupling effect through electron dynamics and vibrational properties has been lacking. Here, we report the first pressure-dependent ultrafast photocarrier dynamics and Raman scattering studies on an iron chalcogenide FeTeSe to explore the interaction between electrons and phonons in this unconventional superconductor. The lifetime of the excited electrons evidently decreases as the pressure increases from 0 to 2.2 GPa, and then increases with further compression. The vibrational properties of the phonon mode exhibit similar behavior, with a pronounced frequency reduction appearing at approximately 2.3 GPa. The dual evidence reveals the enhanced electron–phonon coupling strength with pressure in FeTeSe. Our results give an insight into the role of the electron–phonon coupling effect in iron-based superconductors.

Polaron mobility modulation by bandgap engineering in black phase α-FAPbI3