2D Limit Research Articles

Pushing an Altermagnet to the Ultimate 2D Limit: Symmetry Breaking in Monolayers of GdAlSi.

Altermagnets have emerged as a class of materials combining ferromagnetic properties with vanishing net magnetization. This combination is highly promising for spintronics, especially if a material can be brought to the nanoscale. However, experimental studies of the 2D limit of the altermagnets are lacking. Here, we study epitaxial films on silicon of the Weyl altermagnet GdAlSi ranging from more than a hundred unit cells to a single unit cell. The films do not show any discernible net magnetic moments. Electron transport studies reveal a remarkable transformation. Thick films exhibit the chiral anomaly, whereas symmetry restrictions prevent observation of the anomalous Hall effect in our electron transport measurements. In ultrathin films, a spontaneous anomalous Hall effect manifests itself, indicating a nonrelativistic spin splitting. The transformation is associated with crystal symmetry breaking accompanying the 3D-to-2D crossover. The work highlights the role of dimensionality in altermagnetism and provides a platform for studies aiming at ultracompact spintronics.

Recent Progress in Chemical Vapor Deposition of 2D Magnetic Materials

AbstractMagnetic 2D materials have gotten significant attention due to their unique low‐dimensional magnetism and potential applications in advanced spintronics, providing an perfect platform for investigating magnetic properties at the 2D limit. The chemical vapor deposition (CVD), known for its simplicity and strong controllability, has become a key technique for fabricating ultrathin magnetic nanosheets. This article systematically reviews recent advancements in CVD‐grown magnetic 2D materials, focusing on the effects of growth parameters on material morphologies and properties, and analyzing the construction of heterostructures and their role in magnetic regulation. In addition, various magnetic characterization methods are introduced, and potential applications of these materials in spintronic devices are discussed. By summarizing current challenges, the article provides insights into future research directions, emphasizing the need to improve material stability, Curie temperature, and scalable synthesis to enable practical applications of 2D magnetic materials.

2D and 3D Classification Systems for Adolescent Idiopathic Scoliosis: Clinical Implications and Technological Advances.

Classification systems for Adolescent Idiopathic Scoliosis (AIS) play an important role in guiding both surgical planning and conservative treatments. Traditional 2D classification systems, such as the Lenke, King and Lehnert-Schroth classifications, have been widely used for the clinical diagnosis and treatment of scoliosis. However, with the growing understanding of the three-dimensional nature of scoliosis and advancements in 3D reconstruction technologies, 3D classification systems are gaining increasing attention. This paper reviews the current applications, advantages, and limitations of different 2D and 3D classification systems, focusing on their clinical significance in treatment planning. While 3D classification systems offer clear advantages in capturing the complexity of spinal deformities, their clinical implementation faces challenges such as high costs and technical complexity. Additionally, studies show that computer-assisted technologies, artificial intelligence can significantly improve the accuracy and consistency of classification systems, reducing human errors. The paper also explores the future directions of classification system development, emphasizing the potential of combining 2D and 3D technologies and the impact of these advancements on personalized scoliosis treatment.

Downscaling of Non-Van der Waals Semimetallic W5N6 with Resistivity Preservation.

The bulk phase of transition metal nitrides (TMNs) has long been a subject of extensive investigation due to their utility as coating materials, electrocatalysts, and diffusion barriers, attributed to their high conductivity and refractory properties. Downscaling TMNs into two-dimensional (2D) forms would provide valuable members to the existing 2D materials repertoire, with potential enhancements across various applications. Moreover, calculations have anticipated the emergence of uncommon physical phenomena in TMNs at the 2D limit. In this study, we use the atomic substitution approach to synthesize 2D W5N6 with tunable thicknesses from tens of nanometers down to 2.9 nm. The obtained flakes exhibit high crystallinity and smooth surfaces. Electrical measurements on 15 samples show an average electrical conductivity of 161.1 S/cm, which persists while thickness decreases from 45.6 to 2.9 nm. The observed weak gate-tuning effect suggests the semimetallic nature of the synthesized 2D W5N6. Further investigation of the conversion mechanism elucidates the crucial role of chalcogen vacancies in the precursor for initiating the reaction and strain in propagating the conversion. Our work introduces a desired semimetallic crystal to the 2D material library with mechanistic insights for future design of the synthesis.

Percolative phase transition in few-layered MoSe2 field-effect transistors using Co and Cr contacts.

The metal-to-insulator phase transition (MIT) in two-dimensional (2D) materials under the influence of a gating electric field has revealed interesting electronic behavior and the need for a deeper fundamental understanding of electron transport processes, while attracting much interest in the development of next-generation electronic and optoelectronic devices. Although the mechanism of the MIT in 2D semiconductors is a topic under debate in condensed matter physics, our work demonstrates the tunable percolative phase transition in few-layered MoSe2 field-effect transistors (FETs) using different metallic contact materials. Here, we attempted to understand the MIT through temperature-dependent electronic transport measurements by tuning the carrier density in a MoSe2 channel under the influence of an applied gate voltage. In particular, we have examined this phenomenon using the conventional chromium (Cr) and ferromagnetic cobalt (Co) as two metal contacts. For both Cr and Co, our devices demonstrated n-type behavior with a room-temperature field-effect mobility of 16 cm2 V-1 s-1 for the device with Cr-contacts and 92 cm2 V-1 s-1 for the device with Co-contacts, respectively. With low temperature measurements at 50 K, the mobilities increased significantly to 65 cm2 V-1 s-1 for the device with Cr and 394 cm2 V-1 s-1 for the device with Co-contacts. By fitting our experimental data to the percolative phase transition theory, the temperature-dependent conductivity data show a transition from an insulating-to-metallic behavior at a bias of ∼28 V for Cr-contacts and ∼20 V for Co-contacts. This cross-over of the conductivity can be attributed to an increase in carrier density as a function of the gate bias in temperature-dependent transfer characteristics. By extracting the critical exponents, we find that the transport behavior in the device with Co-contacts aligns closely with the 2D percolation theory. In contrast, the devices with Cr-contacts deviate significantly from the 2D limit at low temperatures.

Recent progress in two-dimensional Bi2O2Se and its heterostructures.

Ever since the identification of graphene, research on two-dimensional (2D) materials has garnered significant attention. As a typical layered bismuth oxyselenide, Bi2O2Se has attracted growing interest not only due to its conventional thermoelectricity but also because of the excellent optoelectronic properties found in the 2D limit. Moreover, 2D Bi2O2Se exhibits remarkable properties, including high carrier mobility, air stability, tunable band gap, unique defect characteristics, and favorable mechanical properties. These properties make it a promising candidate for next-generation electronic and optoelectronic devices, such as logic devices, photodetectors, sensors, energy technologies, and memory devices. However, despite significant progress, there are still challenges that must be addressed for widespread commercial use. This review provides an overview of progress in Bi2O2Se research. We start by introducing the crystal structure and physical properties of Bi2O2Se and a compilation of methods for modulating its physical properties is further outlined. Then, a series of methods for synthesizing high-quality 2D Bi2O2Se are summarized and compared. We next focus on the advancements made in the practical applications of Bi2O2Se in the fields of field-effect transistors (FETs), photodetectors, neuromorphic computing and optoelectronic synapses. As heterostructures induce a new degree of freedom to modulate the properties and broaden applications, we especially discuss the heterostructures and corresponding applications of Bi2O2Se integrated with 0D, 1D and 2D materials, providing insights into constructing heterojunctions and enhancing device performance. Finally, the development prospects for Bi2O2Se and future challenges are discussed.

Synthesis of Two-Dimensional High-Entropy Transition Metal Dichalcogenide Single Crystals.

Two-dimensional (2D) high-entropy transition metal dichalcogenides (HETMDs) have gained significant interest due to their structural properties and correlated possibilities for high-end devices. However, the controlled synthesis of 2D HETMDs presents substantial challenges owing to the distinction in the inherent characteristics among diverse metal elements in the synthesis, such as saturated vapor pressure of precursors and formation energy of products. Here, we present the synthesis of a 2D HETMD single crystal with 0.92 nm thickness through a liquid-phase reaction system, where the metal elements are fed uniformly and simultaneously. The rapid codeposition of different precursors facilitates the formation of high-entropy products, thereby preventing phase separation. The method can be expanded to produce a variety of 2D HETMDs, such as quinary (MoNbTaV)S2, hexahydroxy (MoWNbTaV)S2, and multichalcogenide (MoWNb)SSe. The as-prepared 2D HETMD is an excellent catalyst for the hydrogen evolution reaction (HER), demonstrating the overpotential of 84 mV at 10 mA cm-2 of an individual crystal, which is much better than that of pristine MoS2 (260 mV at 10 mA cm-2). The strategy offers the flexibility to artificially design the element selectivity and properties of HETMD single crystals in the 2D limit, enabling applications across a wide range of advanced fields.

Above curie temperature ultrafast terahertz emission and spin current generation in a two-dimensional superlattice (Fe3GeTe2/CrSb)3

Abstract The increasing demand for denser information storage and faster data processing has fuelled a keen interest in exploring spin currents up to terahertz (THz) frequencies. The emergent two-dimensional (2D) intrinsic magnetic materials constitute a novel and highly controllable platform to access such femtosecond spin dynamics at atomic layer thickness. However, 2D van der Waals magnets are limited by their Curie temperatures (usually at low temperatures) to exhibit the functioning. Here, in a 2D superlattice (Fe3GeTe2/CrSb)3, we demonstrate ultrafast laser-induced spin current generation and THz radiation at room temperature, overcoming the challenge of its Curie temperature being only 206 K. In tandem with time-resolved magneto-optical Kerr effect measurements and first-principle calculations, we further elucidate the origin of the spin currents—a laser-enhanced proximity effect manifested as a laser-induced reduction of interlayer distance and enhanced electron exchange interactions, which causes transient spin polarization in the heterostructure. Our findings present an innovative, magnetic-element-free route for generating ultrafast spin currents in the 2D limit, underscoring the significant potential of laser THz emission spectroscopy in investigating laser-induced extraordinary spin dynamics.

Tunable Mirror-Symmetric Type-III Ising Superconductivity in Atomically-Thin Natural Van der Waals Heterostructures.

Van der Waals (vdW) crystals with strong spin-orbit coupling (SOC) provide great opportunities for exploring unconventional 2D superconductors, wherein new pairing states emerge due to the interplay of SOC with crystalline symmetries, electronic correlations, quenched disorders and external modulation forces, etc. Here, a distinct mirror-symmetry protected Ising pairing state with unprecedented Γ- and M-valley symmetries in natural vdW heterostructures (vdWH) of interweaving tetragonal SnSe and trigonal 1H-TaSe2 monolayers is reported, in which the unidirectional lattice interlocking effectively suppresses the K-valley Ising pairing mechanism by incommensurate charge-density-wave (CDW) transitions. In the 2D limit of an TaSe2/SnSe bilayer with intact basal mirror symmetry (Mz), the mirror-symmetric vdWH Ising superconductors show anomalous in-plane magnetic field B‖-controlled enhancements in the critical temperature Tc, which is completely absent for multilayer vdWHs with broken Mz induced by orthorhombic stacking between nearest-neighbour TaSe2 monolayers. The experimental observations consistently reveal a mirror symmetry-protected type-III Ising state in the inversion asymmetric lattice of 1H-TaSe2, which is predicted to be a mixture of spin-singlet and spin-tripletstates.

Assessment of peroneal tendon lesions using 2-dimensional and 3-dimensional isotropic magnetic resonance imaging with surgical correlation.

Accurate diagnoses of peroneal pathologies remains a challenge due to limitations of conventional 2D (dimensional) imaging, which can impact long-term patient outcomes. This study evaluates MRI accuracy and inter-reader reliability of peroneal compartment pathology for 2D and 3D MRI. A consecutive series of patients who underwent peroneal compartment surgery with preoperative 1.5- or 3.0-Tesla ankle MRIs from 2009 to 2024 included 32 scans (22 with 2D, 10 with 2D+3D) from 31 patients (ages 17-74 years, all genders). Three musculoskeletal readers blinded to surgical findings independently analyzed MRI scans for common peroneal tenosynovitis, peroneus brevis and peroneus longus tenosynovitis, tendinopathy, and tears. Inter-reader reliability and diagnostic performance measures were calculated. Using majority vote, overall accuracy, sensitivity, and specificity for peroneal tendons using 2D MRI were 80%, 81%, and 79%, respectively. Using 3D MRI sequences, whether in isolation or combination with 2D MRI, accuracy, sensitivity, and specificity increased to 85%, 88%, and 83%, respectively. The inter-reader reliability for peroneus brevis lesions was 0.45-0.75 for 2D, 0.25-0.35 for 3D, and 0.31-0.54 for combined 2D+3D, while for peroneus longus lesions, it was 0.45-0.90 for 2D, 0.20-0.71 for 3D, and 0.64-0.81 for combined 2D+3D scans. The inter-reader reliability for tenosynovitis ranged from 0.62-0.64 for 2D, 0.25-0.37 for 3D, and 0.57-0.66 for combined 2D+3D scans. The addition of 3D MRI to 2D high-resolution ankle MRI protocol or 3D MRI alone increases accuracy of peroneal compartment lesion detection with minor decrease in inter-reader reliability for peroneal brevis tendon assessment. Larger studies may help validate our findings.

3D Heisenberg universality in the van der Waals antiferromagnet NiPS3

Van der Waals (vdW) magnetic materials are comprised of layers of atomically thin sheets, making them ideal platforms for studying magnetism at the two-dimensional (2D) limit. These materials are at the center of a host of novel types of experiments, however, there are notably few pathways to directly probe their magnetic structure. We confirm the magnetic order within a single crystal of NiPS3 and show it can be accessed with resonant elastic X-ray diffraction along the edge of the vdW planes in a carefully grown crystal by detecting structurally forbidden resonant magnetic X-ray scattering. We find the magnetic order parameter has a critical exponent of β ~ 0.36, indicating that the magnetism of these vdW crystals is more adequately characterized by the three-dimensional (3D) Heisenberg universality class. We verify these findings with first-principles density functional theory, Monte-Carlo simulations, and density matrix renormalization group calculations.

Tuning the Magnetism in Ultrathin CrxTey Films by Lattice Dimensionality

Abstract2D magnetic crystals with atomic thickness exhibit intriguing physical properties, which have attracted considerable research interest in the related materials’ family, both in fundamental research and in developing spintronic devices. The recent discovery of some non‐van der Waals 2D magnetic crystals expands the systems. Nevertheless, the relationship between the dimensionality of microscopic magnetic exchange interactions and macroscopic magnetic properties at the 2D limit remains to be fully elucidated. Here, we have fabricated mono‐phased continuous ultrathin CrTe2 and Cr3Te4 films by molecular beam epitaxy and elucidated the diverse magnetism tuned by the dimensionality of exchange interactions by a joint study of spin‐polarized scanning tunneling microscopy, magnetization, magneto‐transport measurements, and density functional theory calculations. The transition from a zigzag‐antiferromagnetic order in the monolayer CrTe2 to a ferromagnetic (FM) order in the second‐layer CrTe2 is confirmed, which is driven by their varied in‐plane lattice constants induced change of 2D exchange interactions. A robust FM state with large perpendicular magnetic anisotropy in Cr3Te4 is observed, originating from its strong 3D exchange interactions. The observed evolution of magnetism demonstrates that the dimensionality of magnetic exchange interactions strongly influences magnetism even at the 2D limit.

Intercalation-Induced Monolayer Behavior in Bulk NbSe2.

Superconductivity at the 2D limit is significant for advancing fundamental physics, leading to extensive research on monolayer two-dimensional materials. In particular, monolayer transition metal dichalcogenides such as NbSe2 exhibit Ising superconductivity due to broken in-plane inversion symmetry and strong spin-orbit coupling, which has garnered significant attention. In this letter, we adopted an organic cation intercalation technique to modulate the interlayer interaction of NbSe2 by expanding the interlayer distance, thereby making intercalated NbSe2 behave similarly to monolayer NbSe2. The interlayer distances of NbSe2 intercalated with THA+, CTA+, and TDA+ cations are almost double or triple that of pristine NbSe2. The superconducting transition temperature (Tc) of THA-NbSe2 is comparable to that of pristine NbSe2, while the charge density wave (CDW) transition temperature is higher. The Tc of intercalated NbSe2 decreases with a reduced hole concentration, and the enhanced CDW is ascribed to the dimensional reduction. Notably, the in-plane upper critical field of intercalated NbSe2 significantly exceeds the Pauli paramagnetic limit, which is similar to the Ising superconductivity observed in monolayer NbSe2. Our work demonstrates that the organic cations intercalated two-dimensional materials exhibit behavior similar to their monolayer counterparts, providing a convenient platform for exploring and modulating physical phenomena at the two-dimensional limit.

Mechanisms of Controllable Growth and Ohmic Contact of Two-Dimensional Molybdenum Disulfide: Insight from Atomistic Simulations.

ConspectusTwo-dimensional (2D) semiconducting transition metal dichalcogenides (TMDs), in particular molybdenum disulfide (MoS2), have recently attracted huge interest due to their proper bandgap, high mobility at 2D limit, and easy-to-integrate planar structure, which are very promising for extending Moore's law in postsilicon electronics technology. Great effort has been devoted toward such a goal since the demonstration of protype MoS2 devices with high room-temperature on/off current ratios, ultralow standby power consumption, and atomic level scaling capacity down to sub-1-nm technology node. However, there are still several key challenges that need to be addressed prior to the real application of MoS2-based electronics technology. The controllable growth of wafer-scale single-crystal MoS2 on industry-compatible insulating substrates is the prerequisite of application while the currently synthesized MoS2 films mostly are polycrystalline with limited sizes of single-crystal domains and may involve metal substrates. The precise layer-control is also very important for MoS2 growth since its electronic properties are layer-dependent, whereas the layer-by-layer growth of multilayer MoS2 dominated by the van der Waals (vdW) epitaxy leads to poor thickness uniformity and noncontinuously distributed domains. High density up to 1013 cm-2 of sulfur vacancies (SVs) in grown MoS2 can cause unfavorable carrier scatting and electronic properties variations and will inevitably disturb the device performance. The dangling-bond-free surface of MoS2 gives rise to an inherent vdW gap at metal-semiconductor (M-S) contact, which leads to high electrical resistance and poor current-delivery capability at the contact interface and thereby substantially limits the performances of MoS2 devices.In this Account, we briefly review recent experimental and theoretical attempts for addressing the aforementioned challenges and present our own insights from atomistic simulations. We theoretically revealed the vital role of substrate steps for guiding unidirectional nucleation of monolayer MoS2 and uniform nucleation and edge-aligned growth of bilayer MoS2 by advanced simulations. The established thermodynamic mechanisms have successfully directed the experimental works on the controllable growth of 2 in. single-crystal monolayer and centimeter-scale uniform bilayer MoS2. The postgrowth repair mechanism of SV defect in MoS2 via thiol chemistry treatment has been theoretically explored with the consideration of side reaction of surface functionalization to help experimentally reduce SV defect density by 75%. Beyond the atomic level understanding, theoretical simulations proposed the electronic states hybridization mechanism across the semimetal-MoS2 vdW interface, thereby guiding experimental effort for realizing Ohmic contact at the MoS2-Sb(0112) vdW interface with record-low contact resistance.These advances provide a sound basis with an atomic-level understanding for addressing the related issues. However, there are still notable gaps in terms of system size and time scale of dynamics between atomistic simulations and experimental observations for the studies of MoS2 growth and interfaces. The combination of multiscale simulations and artificial intelligence technology is expected to narrow these gaps and provide a more insightful understanding of the controllable growth and interfacial properties modulation of MoS2. We conclude the Account with the standing challenges and outlook on future research directions from the theoretical perspective.

Characterization of the dynamic forces transmitted to the support of a railway track, due to the roughness of wheels and rails - 3D finite element approach

Among the causes of railway vibrations, rail and wheel roughness is recognized as a major contribution. The excitation mechanism at work when rough wheels run on rough rails can be assimilated to a prescribed relative displacement between the wheels and the rails. This article deals with the modeling of this wheel/rail interaction phenomenon, using a 3D FEM approach. The input excitation data is the combined wheel / rail roughness spectrum, while the sought output is the spectrum of dynamic forces transmitted to the support. Characterization of these dynamic forces can be used, for instance, to assess the anti-vibration performance of a track. The presented approach overcomes the limitations of 2D or analytical approaches commonly encountered in dynamic studies of railway tracks: (a) It takes advantage of the finite element modeling flexibility, compared to analytical approaches, which are developed for specific configurations. (b) It can account for the infrastructure's dynamic flexibility, whether it is invariant in the longitudinal direction or not. (c) It can account for the 3D dynamic behavior of the track. As an illustration, the method is applied to a floating slab track, thereby showing the importance of the transverse modal behavior of the track in this case.

Controlling Ultrafast Magnetization Dynamics via Coherent Phonon Excitation in a Ferromagnet Monolayer.

Exploring ultrafast magnetization control in 2D magnets via laser pulses is established, yet the interplay between spin dynamics and the lattice remains underexplored. Utilizing real-time time-dependent density functional theory (rt-TDDFT) coupled with Ehrenfest dynamics and nonadiabatic molecular dynamics (NAMD) simulations, we systematically investigate the laser-induced spin-nuclei dynamics with pre-excited A1g and E2g coherent phonons in the 2D ferromagnet Fe3GeTe2 (FGT) monolayer. Selective pre-excitation of coherent phonons under ultrafast laser irradiation significantly alters the local spin moment of FGT, consequently inducing additional spin loss attributed to the nuclear motion-induced asymmetric interatomic charge transfer. Excited spin-resolved charge undergoes a bidirectional spin-flip between spin-down and spin-up states, characterized by a subtle change in the spin moment within approximately 100 fs, followed by unidirectional spin-flip, which will further contribute to the spin moment loss of FGT within tens of picoseconds. Our results shed light on the coupling of coherent phonons with magnetization dynamics in 2D limit.

Proximity coupling induced two dimensional magnetic order in EuO-based synthetic ferrimagnets

Proximity effects allow for the adjustment of magnetic properties in a physically elegant way. If two thin ferromagnetic (FM) films are brought into contact, electronic coupling alters their magnetic exchange interaction at their interface. For a low-TC\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$T_C$$\\end{document} rare-earth FM coupled to a 3d transition metal FM, even room temperature magnetism is within reach. In addition, magnetic proximity coupling is particularly promising for increasing the magnetic order of metastable materials such as europium monoxide (EuO) beyond their bulk TC\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$T_C$$\\end{document}, since neither the stoichiometry nor the insulating properties are modified. We investigate the magnetic proximity effect at Fe/EuO and Co/EuO interfaces using hard X-ray photoelectron spectroscopy. By exciting the FM layers with circularly polarized light, magnetic dichroism is observed in angular dependence on the photoemission geometry. In this way, the depth-dependence of the magnetic signal is determined element-specifically for the EuO and 3d FM parts of the bilayers. In connection with atomistic spin dynamics simulations, the thickness of the EuO layer is found to be crucial, indicating that the observed antiferromagnetic proximity coupling is a short-ranged and genuine interface phenomenon. This fact turns the bilayer into a strong synthetic ferrimagnet. The increase in magnetic order in EuO occurs in a finite spatial range and is therefore particularly strong in the 2D limit—a counterintuitive but very useful phenomenon for spin-based device applications.

Epitaxial growth of quasi-2D van der Waals ferromagnets on crystalline substrates

Intrinsic magnetism in van der Waals materials has instigated interest in exploring magnetism in the 2D limit for potential applications in spintronics and also in understanding novel control of 2D magnetism via variation of layer thickness, gate tunability and magnetoelectric effects. The chromium telluride (CrxTey) family is an interesting subsection of ferromagnetic materials with highTCvalues, also presenting diverse stoichiometry arising from self-intercalation of Cr. Apart from the layered CrTe2system, the other non-layered CrxTeycompounds also offer exceptional magnetic properties, and a novel growth technique to grow thin films of these non-layered compounds offers exciting possibilities for ultra-thin spin-based electronics and magnetic sensors. In this work, we discuss the role of crystalline substrates in chemical vapor deposition growth of non-layered 2D ferromagnets, where the crystal symmetry of the substrate as well as the misfit and strain are the key players governing the growth mechanism of ultra-thin Cr5Te8, a non-layered ferromagnet. The magnetic studies of the as-grown Cr5Te8reveal the signatures of co-existing soft and hard ferromagnetic phases, which makes this system an intriguing system to search for emergent topological phases, such as magnetic skyrmions.

Incommensurate charge super-modulation and hidden dipole order in layered kitaev material α-RuCl3

The magnetism of Kitaev materials has been widely studied, but their charge properties and the coupling to other degrees of freedom are less known. Here we investigate the charge states of α-RuCl3, a promising Kitaev quantum spin liquid candidate, in proximity to graphite. We discover that few-layered α-RuCl3 experiences a clear modulation of charge states, where a Mott-insulator to weak charge-transfer-insulator transition in the 2D limit occurs by means of heterointerfacial polarization. More notably, distinct signals of incommensurate charge and lattice super-modulations, regarded as an unconventional charge order, accompanied in the insulator. Our theoretical calculations have reproduced the incommensurate charge order by taking into account the antiferroelectricity of α-RuCl3 that is driven by dipole order in the internal electric fields. The findings imply that there is strong coupling between the charge, spin, and lattice degrees of freedom in layered α-RuCl3 in the heterostructure, which offers an opportunity to electrically access and tune its magnetic interactions inside the Kitaev compounds.

Anisotropic Spin Fluctuations Induced by Spin-Orbit Coupling in a Misfit Layer Compound (LaSe)1.14(NbSe2).

Spin-orbit coupling (SOC) has significant effects on the superconductivity and magnetism of transition metal dichalcogenides (TMDs) at the 2D limit. Although 2D TMD samples possess many exotic properties different from those of bulk samples, experimental characterization in this field is still limited, especially for magnetism. Recent studies have revealed that bulk misfit layer compounds (MLCs) with (LaSe)1.14(NbSe2)n = 1,2 exhibit an Ising superconductivity similar to that of heavily electron-doped NbSe2 monolayers. This offers an opportunity to study the effect of SOC on the magnetism of 2D TMDs. Here, the possible SOC effect in (LaSe)1.14(NbSe2) is investigated by measuring nuclear magnetic resonance (NMR) and electrical transport. It is found that the LaSe layer not only functions as a charge reservoir for transferring electrons into the NbSe2 layer but also remarkably influences the local electronic environment around the 93Nb nuclei. More importantly, the significant SOC induces both a weak antilocalization (WAL) effect and anisotropic spin fluctuations in noncentrosymmetric NbSe2 layers. The present work contributes to a deep understanding of the role of the SOC effect in 2D TMDs and supports MCLs as an intriguing platform for exploring exotic physical properties within the 2D limit.