Electrons Research Articles

Author Correction: Intervalley coherence and intrinsic spin–orbit coupling in rhombohedral trilayer graphene

Author Correction: Intervalley coherence and intrinsic spin–orbit coupling in rhombohedral trilayer graphene

An Actinide Complex with a Nucleophilic Allenylidene Ligand.

The reaction of [Cp3Th(3,3-diphenylcyclopropenyl)] (Cp = η5-C5H5) with 1 equiv of lithium diisopropylamide (LDA) results in cyclopropenyl ring opening and formation of the thorium allenylidene complex, [Li(Et2O)2][Cp3Th(CCCPh2)] ([Li(Et2O)2][1]), in good yield. Additionally, deprotonation of [Cp3Th(3,3-diphenylcyclopropenyl)] with 1 equiv of LDA, in the presence of 12-crown-4 or 2.2.2-cryptand, results in the formation of discrete cation/anion pairs, [Li(12-crown-4)(THF)][Cp3Th(CCCPh2)] ([Li(12-crown-4)(THF)][1]) and [Li(2.2.2-cryptand)][Cp3Th(CCCPh2)] ([Li(2.2.2-cryptand)][1]), respectively. Interestingly, the complex [Li(Et2O)2][1] undergoes dimerization upon standing at room temperature, resulting in the formation of [Cp2Th(μ:η1:η3-CCCPh2)]2 (2), via loss of LiCp. The reaction of [Li(Et2O)2][1] with MeI results in electrophilic attack at the Cγ carbon atom, leading to the formation of a thorium acetylide complex, [Cp3Th(C≡CC(Me)Ph2)] (3), which can be isolated in 83% yield upon workup, whereas the reaction of [Li(Et2O)2][1] with benzophenone results in the formation of 1,1,4,4-tetraphenylbutatriene (4) in 99% yield, according to integration against an internal standard. Density functional theory (DFT) calculations performed on [1]- and 2 reveal significant electron delocalization across the allenylidene ligand. Additionally, calculations of the 13C NMR chemical shifts for the Cα, Cβ, and Cγ nuclei of the allenylidene ligand were in good agreement with the experimental shifts. The calculations reveal modest deshielding induced by spin-orbital effects originating at Th due to the involvement of the 5f orbitals in the Th-C bonds. According to a DFT analysis, the cyclopropenyl ring-opening reaction proceeds via [Cp3Th(η1-3,3-Ph2-cyclo-C3)]- (IM), which features a carbanion character at Cβ.

Intracage vibrations and Zeeman effect in Y3N@C80 single-molecule transistors

Clusterfullerenes, which contain a cluster rather than single-atom inclusions, exhibit more complex internal structures and greater degrees of freedom for motion. Trimetallic nitride clusterfullerenes have attracted significant attention due to their diversity and potential applications, among which Y3N@C80 stands out for its charge-transfer characteristics in electronic excitations, owing to the unique distribution of molecular orbitals near the Fermi level. Here, we have fabricated single-molecule transistor devices using Y3N@C80. Transport measurements at liquid helium temperature revealed a series of excited state energy levels, which were matched to corresponding vibrational modes through comparison with Raman spectra and density functional theory calculations. Additionally, we measured charge-state-dependent magnetic responses, revealing the electron and spin-filling patterns of the molecular orbitals in Y3N@C80. These results enhance our understanding of the dynamics and molecular spin–orbit characteristics of clusterfullerenes, indicating their potential for multifunctional applications.

Quantum Equation-of-Motion Method with Single, Double, and Triple Excitations.

The quantum equation-of-motion (qEOM) method with single and double excitations (qEOM-SD) has been proposed to study electronically excited states, but it fails to handle states dominated by double excitations. In this work, we reformulate the qEOM method within the effective Hamiltonian framework that satisfies the killer condition, and then present an efficient implementation incorporating single, double, and triple excitations. To reduce computational complexity, we employ point-group symmetry and perturbation theory to screen triple excitations, effectively reducing the scaling from No6Nv6 to No5Nv5, where No and Nv are the numbers of occupied and virtual spin orbitals, respectively. Furthermore, we account for the effect of neglected triple excitations by introducing a perturbative correction to the excitation energy. We apply this method to challenging cases where the qEOM-SD method exhibits significant errors, such as the 2 1Δ state of CH+ and the 2 1Σ state of HF. Our new method achieves energy errors below 0.18 eV while incorporating less than 8.2% of triple excitations. Additionally, we extend the operator screening technique to the quantum subspace expansion method for the efficient inclusion of selected triple excitations.

Initialization-free multistate memristor: Synergy of spin–orbit torque and magnetic fields

Spin–orbit torque (SOT)-based perpendicularly magnetized memory devices with multistate memory have garnered significant interest due to their applicability in low-power in-memory analog computing. However, current methods are hindered by initialization problems, such as prolonged writing duration, and limitations, on the number of magnetic states. Consequently, a universal method for achieving multistate in perpendicular magnetic anisotropy (PMA)-based stacks remains elusive. Here, we propose a general experimental method for achieving multistate without any initialization step in SOT-driven magnetization switching by integrating an external out-of-plane magnetic field. Motivated by macrospin calculations coupled with micromagnetic simulations, which demonstrate the plausibility of magnetization state changes due to out-of-plane field integration, we experimentally verify multistate behavior in Pt/Co/Pt and W/Pt/Co/AlOx stacks. The occurrence of multistate behavior is attributed to intermediate domain states with Néel domain walls. We achieve repeatable 18 multistate configurations with a minimal reduction in retentivity through energy barrier measurements, paving the way for efficient analog computing.

Cumulated Effects of Magnetic Field, Electron–Phonon and Spin–Orbit Interaction on Thermodynamics Properties of Mono Layer Graphene

Cumulated Effects of Magnetic Field, Electron–Phonon and Spin–Orbit Interaction on Thermodynamics Properties of Mono Layer Graphene

The p : q resonance for dissipative spin–orbit problem in celestial mechanics

The p : q resonance for dissipative spin–orbit problem in celestial mechanics

Prediction of metal-free Stoner and Mott-Hubbard magnetism in triangulene-based two-dimensional polymers.

Ferromagnetism and antiferromagnetism require robust long-range magnetic ordering, which typically involves strongly interacting spins localized at transition metal atoms. However, in metal-free systems, the spin orbitals are largely delocalized, and weak coupling between the spins in the lattice hampers long-range ordering. Metal-free magnetism is of fundamental interest to physical sciences, unlocking unprecedented dimensions for strongly correlated materials and biocompatible magnets. Here, we present a strategy to achieve strong coupling between spin centers of planar radical monomers in π-conjugated two-dimensional (2D) polymers and rationally control the orderings. If the π-states in these triangulene-based 2D polymers are half-occupied, then we predict that they are antiferromagnetic Mott-Hubbard insulators. Incorporating a boron or nitrogen heteroatom per monomer results in Stoner ferromagnetism and half-metallicity, with the Fermi level located at spin-polarized Dirac points. An unprecedented antiferromagnetic half-semiconductor is observed in a binary boron-nitrogen-centered 2D polymer. Our findings pioneer Stoner and Mott-Hubbard magnetism emerging in the electronic π-system of crystalline-conjugated 2D polymers.

Ultrafast antiferromagnetic switching of Mn2Au with laser-induced optical torques

Ultrafast manipulation of the Néel vector in metallic antiferromagnets most commonly occurs by generation of spin-orbit (SOT) or spin-transfer (STT) torques. Here, we predict another possibility for antiferromagnetic domain switching by using novel laser optical torques (LOTs). We present results of atomistic spin dynamics simulations from the application of LOTs for all-optical switching of the Néel vector in the antiferromagnet Mn2Au. The driving mechanism takes advantage of the sizeable exchange enhancement, characteristic of antiferromagnetic dynamics, allowing for picosecond 90 and 180-degree precessional toggle switching of the Néel vector with laser fluences on the order of mJ/cm2. A special symmetry of these novel torques greatly minimises the over-shooting effect common to precessional spin switching by SOT and STT methods. We demonstrate the opportunity for LOTs to produce deterministic, non-toggle switching of single antiferromagnetic domains. Lastly, we show that even with sizeable ultrafast heating by laser in metallic systems, there exist a large interval of laser parameters where the LOT-assisted toggle and preferential switchings in magnetic grains have probabilities close to one. The proposed protocol could be used on its own for all-optical control of antiferromagnets for computing or memory storage, or in combination with other switching methods to lower energy barriers and/or to prevent over-shooting of the Néel vector.

Unveiling novel drug delivery mechanism: Cisplatin’s bonding behaviour with BC4N Nanostructure

Recent advancements in nanotechnology have opened avenues to address the selectivity challenges in targeted drug delivery systems, minimizing adverse effects. While carbon nanotubes (CNTs) have gained traction as drug carriers, their B, N-containing counterpart, pristine boron carbonite (p-BC4N), remains underexplored. This study investigates the possibility of pristine boron carbonite (p-BC4N) nanotubes as a drug carrier for the anticancer medication cisplatin (CPT). Using first-principles Density Functional Theory (DFT) simulations, we examined the interaction between CPT and p-BC4N nanotubes, revealing favourable adsorption energies (−0.523 eV) due to orbital interactions and charge transfer between the C 2p orbitals of BC4N and the 1 s orbitals in H of CPT. Ab initio molecular dynamics (AIMD) simulations confirmed the stability of the system at room temperature. Furthermore, pH and temperature-dependent desorption measurements demonstrated the effectiveness of p-BC4N nanotubes as a promising candidate for CPT drug delivery, highlighting their potential in targeted cancer therapy. This work opens up new avenues for the development of nanotechnology-based drug delivery systems.

Theoretical study on the spectrum properties of tellurium iodide cation

The molecular potential energy function plays an important role in many fields. In this paper, the icMRCI + Q method was utilized to compute the potential energy and dipole moments for 22 Λ-S states and 51 Ω states of the TeI+ system. Two basis sets (AVQZ-PP and AWCVQZ-PP) were employed to compute the TeI+ system, with the results indicating that the AVQZ-PP basis set yielded more accurate results. Therefore, all calculations in this paper are based on this basis set. Furthermore, to ensure the accuracy of the results, a comparison was conducted on the spectral parameters of the ground state and two excited states of the molecular ion within the same main group. Given the significant impact of spin–orbit coupling, as indicated by the calculated SO matrix elements, our discussion will predominantly center on the avoidance of crossovers in the Ω states. Finally, the Franck-Condon factors, Einstein coefficients and radiative lifetime between these two states were calculated from the data of the transition between the X3Σ0+-↔11Σ0++ of the TeI+ molecule.

The electronic and optical properties of group III-V semiconductors: Arsenides and antimonides

Investigating the structural, electronic, and optical properties of zinc-blende III-V semiconductors, particularly arsenides, and antimonides, which are crucial for optoelectronic devices such as transistors, infrared detectors, and quantum technologies due to their wide range of direct bandgaps. In this work, we have employed a first-principles approach integrating G0W0 with the HSE06 hybrid functional and spin–orbit coupling (SOC) to study their fundamental properties. Traditional Density Functional Theory (DFT) methods, particularly those using Generalized Gradient Approximation (GGA) PBE functionals, tend to underestimate bandgaps, leading to discrepancies with experimental results. To address this, our study corrects the bandgap underestimation and refines the calculation of optical constants, including the dielectric function, refractive index, extinction coefficient, and absorption coefficient. Moreover, the optimized lattice constants and electronic properties derived from our computational model strongly correlate with experimental data, demonstrating the model’s reliability in predicting material properties. The findings suggest that our methods can be applied to arsenides and antimonides, offering a pathway to designing materials with optoelectronic properties involving III-V compounds and their complex heterostructures for advanced device applications.

JWST reveals the rapid and strong day-side variability of 55 Cancri e

Context. The nature of the close-in rocky planet 55 Cnce is puzzling, despite it having been observed extensively. Its optical and infrared occultation depths show temporal variability, in addition to a phase curve variability observed in the optical. Aims. We wish to explore the possibility that the variability originates from the planet being in a 3:2 spin–orbit resonance, and thus showing different sides during occultations. We proposed and were awarded Cycle 1 time at the James Webb Space Telescope (JWST) to test this hypothesis. Methods. JWST/NIRCam (Near Infrared Camera) observed five occultations (secondary eclipses) of the planet – of which four were observed within a week – simultaneously at 2.1 and 4.5 µm. While the former gives band-integrated photometry, the latter provides a spectrum between 3.9–5.0 µm. Results. We find that the occultation depths in both bandpasses are highly variable and change between a non-detection (−5 ± 6 ppm and 7 ± 9 ppm) to 96 ± 8 ppm and 119−19+34 ppm at 2.1 µm and 4.5 µm, respectively. Interestingly, the variations in both bandpasses are not correlated and do not support the 3:2 spin-orbit resonance explanation. The measured brightness temperature at 4.5 µm varies between 873–2256 K and is lower than the expected day-side temperature of bare rock with no heat redistribution (2500 K), which is indicative of an atmosphere. Our atmospheric retrieval analysis of occultation depth spectra at 4.5 µm finds that different visits statistically favour various atmospheric scenarios including a thin outgassed CO/CO2 atmosphere and a silicate rock vapour atmosphere. Some visits even support a flat line model. Conclusions. The observed variability could be explained by stochastic outgassing of CO/CO2, which is also hinted at by retrievals. Alternatively, the variability observed at both 2.1 and 4.5 µm could be the result of a circumstellar patchy dust torus generated by volcanism on the planet.

Insights into the removal of sulfamethazine and sulfonamide-resistant bacteria from wastewater by Fe-Mn spinel oxide modified cow manure biochar activated peroxymonosulfate: A nonradical pathway regulated by enhanced adsorption and 3d orbital electron reconstruction

Effectively regulating nonradical pathways is crucial for adapting to complex water environments in sulfate radical-based advanced oxidation processes (SR-AOPs). This study prepared manganese ferrite-modified cow-manure biochar composites (BC-FM) as peroxymonosulfate activators to remove sulfamethazine (SMT) and sulfonamide-resistant bacteria (SA-ARB) from wastewater. The extensive conjugated graphitic structure in biochar induced Fe 3d orbital electron reconstruction, promoting empty orbitals formation and enhancing peroxymonosulfate inner-sphere complexation. This facilitated 100 % electron-transfer-dominated nonradical regulation. BC-FM exhibited remarkable catalytic performance, with apparent rate constant of 0.170 min−1 for SMT, inactivating ∼8.6 log of SA-ARB, and effectively blocking horizontal transfer of antibiotic resistance genes in both single and complex pollution systems (SMT/SA-ARB). Moreover, ion leaching experiments, cycling tests, real-water experiments, fluidized-bed and fixed-bed experiments demonstrated BC-FM’s potential for prolonged utilization and practical implementation. This study offers new insights into designing high-performance, environment-friendly bimetal catalysts and provides a basis for remediating organic contaminants with SR-AOPs in livestock wastewater.

Chemical vapor deposition assisted the construction of Fe clusters modified single-atom Fe sites for efficient ORR catalysis

Iron-based atomic single-site catalysts are a type of promising catalyst for oxygen reduction reactions. However, these catalysts are still faced with challenges such as insufficient catalytic activity and poor stability. Fe clusters and Fe single atoms were simultaneously loaded on porous carbon using chemical vapor deposition in this study. The aim is to induce the redistribution of electronic clouds on Fe single-atom sites through Fe clusters, improving their adsorption capacity for oxygen reduction reaction intermediates, and thus obtaining highly active catalysts for oxygen reduction reaction. Under alkaline conditions, the ORR activity of FeSA/FeAC@NC (half-wave potential E1/2 of 0.90 VRHE) was significantly higher than that of commercial Pt/C (0.87 VRHE) and FeSA@NC (0.87 VRHE). Furthermore, FeSA/FeAC@NC exhibited exceptional durability, with 97.5% current retention in the i-t stability test for 10,000s. Additionally, the zinc-air battery assembled with FeSA/FeAC@NC showed a power density of 225 mW cm-2 and an energy density of 1082.2 Wh kgZn-1, demonstrating considerable potential for practical applications.

Design and first tests of the trapped electrons experiment T-REX.

Gyrotrons are essential for electron cyclotron resonance heating in fusion reactors, making efficient operation crucial for advancing fusion energy. Past experiments revealed instability issues due to trapped electrons in the magnetron injection gun (MIG) region, causing undesired currents and operational failures. To address this, tight manufacturing tolerances are required for the MIG geometry [Pagonakis etal., Phys. Plasmas 23, 023105 (2016)]. We present the initial findings of the trapped electrons experiment developed at the Swiss Plasma Center, designed to understand the physics of electron clouds in gyrotron MIGs. T-REX replicates MIG geometries, as well as their typical electric and magnetic fields, and it is supported by 2D particle-in-cell simulations with the FENNECS code [Le Bars etal., Phys. Plasmas 29, 082105 (2022); Le Bars, Ph.D. thesis, EPFL, Lausanne, 2023]. The setup includes two coaxial electrodes in a vacuum chamber atop a superconducting magnet, with a central electrode biased to negative DC voltages and an outer one at the ground, creating a radial electric field (1-2MV/m) and an axial magnetic field (B < 0.4T). This setup mimics Penning-Malmberg traps. We present the experimental device and first findings on current distribution and also a qualitative comparison with FENNECS simulations [Le Bars etal., Comput. Phys. Commun. 303, 109268 (2024)]. Planned diagnostics include optical emission spectroscopy, phosphor screen imaging, streak camera imaging, and potentially electric field distribution via the Stark effect. This research aims to enhance gyrotron performance and reliability in fusion energy systems.

Constructing ultralow-loading Cu single atoms/Fe2O3 particles on Nb2C MXenes for efficient utilization of atomic H to boost electrochemical debromination

Bromate is a commonly identified carcinogenic and genotoxic disinfection byproduct in water. Electrochemical debromination is an environmentally friendly and effective approach but it often suffers the limited reducing atomic H (H*) ability and high metal catalyst dosage. In this study, a unique composite catalyst comprised of ultra-low loading Cu single atoms (0.016 wt%) and Fe2O3 nanoparticles supported on a Nb2C MXene (denoted as Cu0.2/Fe0.1/Nb2C) was synthesized by one-step high-temperature molten salt method. The Cu0.2/Fe0.1/Nb2C significantly outperformed the Nb2C, Cu0.2/Nb2C and Fe0.1/Nb2C counterparts in the electrochemical debromination with a 94.2 % removal efficiency of bromate. It is revealed that the introducing of Cu single atoms, efficiently promotes the adsorption of H* and inhibition of competitive H2 evolution. The incorporation of Fe2O3 nanoparticles significantly increased the electronic metal-support interaction effect between the metal components and Nb2C, thereby forming a noticeable electronic cloud bridge to facilitate efficient charge transfer. Ultimately, the synergistic interplay between Cu single atoms and Fe2O3 nanoparticles plays a crucial role in achieving the remarkable removal performance of bromate. This work not only presents a significant instance of a synergistic catalyst involving metal single atoms and metal nanoparticles for effective electrochemical debromination but also advances the understanding of the electronic metal-support interaction.

Control of spin–orbit torque-driven domain nucleation through geometry in chirally coupled magnetic tracks

The interfacial Dzyaloshinskii–Moriya interaction (DMI) can be exploited in magnetic thin films to realize lateral chirally coupled systems, providing a way to couple different sections of a magnetic racetrack and realize interconnected networks of magnetic logic gates. Here, we systematically investigate the interplay between spin–orbit torques, chiral coupling, and the device design in domain wall racetracks. We show that the current-induced domain nucleation process can be tuned between single-domain nucleation and repeated nucleation of alternate domains by changing the orientation of an in-plane patterned magnetic region within an out-of-plane magnetic racetrack. Furthermore, by combining experiments and micromagnetic simulations, we show that the combination of damping-like and field-like spin–orbit torques with DMI results in selective domain wall injection in one of two arms of a Y-shaped device depending on the current density. Such an element constitutes the basis of domain wall based demultiplexer, which is essential for distributing a single input to any one of the multiple outputs in logic circuits. Our results provide input for the design of reliable and multifunctional domain wall circuits based on chirally coupled interfaces.

Multiple Topological Phases with Electronic Correlation in Intrinsic Ferromagnetic Semimetal VI3 Monolayer.

2D topological materials with magnetic ordering have become hot topics due to their nontrivial band topology and quantum states. In this work, the second-order topological states and evolution of linear band crossing are successfully predicted utilizing the effective k· p and tight binding models in the intrinsic ferromagnetic VI3 monolayer under various effective Hubble interaction Ueff. Upon inclusion of spin orbit coupling, a small bandgap (Eg-1) of 12.7 meV is opened with a Chern invariant C = -1 at Ueff = 0 eV. The Eg-1 undergoes a transition from the non-trivial state to trivial state at Ueff = 0.80 eV, accompanied by the appearance of Dirac cone. Remarkably, the increase of Ueff causes the band inversion and adjustment of crystal symmetry, resulting in two unreported coexistingtopological bandgaps (Eg-2 and Eg-3). Furthermore, a gapless node-loop appears at Ueff = 1.06 eV and disappears at Ueff = 1.09 eV around Γ point. Moreover, for the first time, the existence of second-order topological states with quantized corner fractional charges (e/3) is also observed in the VI3 monolayer at Ueff ≥0.96 eV. These results make the VI3 monolayer a compelling candidate for exploring topological devices.

Tidal evolution and spin–orbit dynamics for bodies in the viscous regime

Tidal evolution and spin–orbit dynamics for bodies in the viscous regime