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Insomnia disorder (ID) is neurobiologically heterogeneous and often eludes characterization by traditional group-level neuroimaging. Subtyping based on neuroimaging and clinical data offers a promising strategy for identifying biologically and clinically meaningful ID subgroups. To address this need, we developed a Gray Matter Population Graph Attention Autoencoder (GM-PGAAE) to subtype insomnia disorder in a cohort comprising 140 patients diagnosed with ID and 57 matched healthy controls. Each subject was represented as a node defined by atlas-based gray matter (GM) volumes. Population edges combined imaging-derived intersubject correlations with clinical similarity via a Hadamard product, generating an adjacency matrix that jointly encodes structural and phenotypic relationships. A Graph Attention Autoencoder learned low-dimensional embeddings that adaptively weighted informative intersubject connections, and clustering these embeddings identified distinct subtypes. Regional and network-level differences were further assessed using Voxel-Based Morphometry (VBM) and individualized differential structural covariance networks (IDSCNs). Through this framework, two ID subtypes were identified. Compared with Subtype 2, Subtype 1 showed higher symptom severity and greater GM reductions–particularly in the cerebellar vermis, thalamus, middle occipital cortex, fusiform gyrus, and paracentral lobule–alongside negative associations between GM volume and clinical scores. IDSCNs further revealed reduced thalamocortical and subcortical Z-scores in Subtype 1, indicating subtype-specific network alterations. Overall, GM-PGAAE integrates structural MRI and clinical measures to derive individualized embeddings and delineate biologically distinct ID subtypes.

Kagome superconductors AV 3 Sb 5 (A = K, Rb, and Cs) have attracted enormous interest due to the coexistence of charge density wave (CDW) order, unconventional superconductivity (SC) and anomalous Hall effect (AHE). In this paper, we reported an intensive investigation on Cs(V 1− x Ta x ) 3 Sb 5 single crystals with systematic Ta doping. Ta was confirmed to be doped into V-site in the Kagome layer from both single crystal X-ray diffraction structural refinement and scanning transmission electron microscopy observation. The highest Ta doping level was found to be about 16%, which is more than twice as much as 7% in Nb-doped CsV 3 Sb 5 . With the increase of Ta doping, CDW order was gradually suppressed and finally vanished when the doping level reached to more than 8%. Meanwhile, superconductivity was enhanced with a maximum critical temperature ( T c) of 5.3 K, which is the highest T c in the bulk crystal of this Kagome system at ambient pressure so far. The μ 0 H c2 (T) behavior demonstrates that the system is still a two-band superconductor after Ta doping. Based on the electrical transport measurement, a phase diagram was set up to exhibit the evolution of CDW and SC in the Cs(V 1− x Ta x ) 3 Sb 5 system. These findings pave a new way to search for new superconductors with higher T c in the AV 3 Sb 5 family and establish a new platform for tuning and controlling the multiple orders and superconducting states.

The century-long development of surface sciences has witnessed the discoveries of a variety of quantum states. In the recently proposed “obstructed atomic insulators”, symmetric charges are pinned at virtual sites where no real atoms reside. The cleavage through these sites could lead to a set of obstructed surface states with partial electronic occupation. Here, utilizing scanning tunneling microscopy, angle-resolved photoemission spectroscopy and first-principles calculations, we observe spectroscopic signature of obstructed surface states in SrIn 2 P 2 . We find that a pair of surface states that are originated from the pristine obstructed surface states split in energy by a unique surface reconstruction. The upper branch is marked with a striking differential conductance peak followed by negative differential conductance, signaling its localized nature, while the lower branch is found to be highly dispersive. This pair of surface states is in consistency with our calculational results. Our finding not only demonstrates a surface quantum state induced by a new type of bulk-boundary correspondence, but also provides a platform for exploring efficient catalysts and related surface engineering. The authors observe spectroscopic signature of obstructed surface states on the (0001) plane of SrIn 2 P 2 . Due to structural reconstruction, the surface state undergoes an adiabatic evolution and split into two branches, the upper of which being spatially localized with unusual negative differential conductance.

Kagome lattices host flat bands due to their frustrated lattice geometry, which leads to destructive quantum interference of electron wave functions. Here, we report imaging of the kagome flat band localization in real-space using scanning tunneling microscopy. We identify both the Fe 3 Sn kagome lattice layer and the Sn 2 honeycomb layer with atomic resolution in kagome antiferromagnet FeSn. On the Fe 3 Sn lattice, at the flat band energy determined by the angle resolved photoemission spectroscopy, tunneling spectroscopy detects an unusual state localized uniquely at the Fe kagome lattice network. We further show that the vectorial in-plane magnetic field manipulates the spatial anisotropy of the localization state within each kagome unit cell. Our results are consistent with the real-space flat band localization in the magnetic kagome lattice. We further discuss the magnetic tuning of flat band localization under the spin–orbit coupled magnetic kagome lattice model. Direct imaging and tuning of flat band localization in kagome materials remains a challenge. Here, scanning tunneling microscopy and photoemission spectroscopy are used to study FeSn, revealing real-space localization and magnetic tuning of the flat band state within the Fe 3 Sn kagome lattice layer.

Understanding how time-reversal symmetry (TRS) breaks in quantum materials is key to uncovering new states of matter and advancing quantum technologies. However, unraveling the interplay between TRS breaking, charge order, and superconductivity in kagome metals continues to be a compelling challenge. Here, we investigate the kagome metal Cs(V 1− x Nb x ) 3 Sb 5 with x  = 0.07 using muon spin rotation ( μ SR), alternating current (AC) magnetic susceptibility, and scanning tunneling microscopy (STM), under combined tuning by chemical doping, hydrostatic pressure, magnetic field, and depth from the surface. We find that TRS breaking in the bulk emerges below 40 K—lower than the charge order onset at 58 K—while near the surface, TRS breaking onsets at 58 K and is twice as strong. Niobium doping raises the superconducting critical temperature from 2.5 K to 4.4 K. Under pressure, both the critical temperature and superfluid density double, with TRS-breaking superconductivity appearing above 0.85 GPa. These findings reveal a depth-tunable TRS-breaking state and unconventional superconducting behavior in kagome systems. Kagome systems are a rich playground to explore the interplay between superconductivity and charge order. Here, the authors present a comprehensive muon spin rotation analysis, coupled with scanning tunnelling microscopy, under various tuning parameters including chemical doping, depth and hydrostatic pressure to investigate time-reversal symmetry-breaking in Nb-doped CsV 3 Sb 5 .

Kagome lattice can host abundant exotic quantum states such as superconductivity and charge density wave (CDW). Recently, successive orders of A-type antiferromagnetism (AFM), CDW and canted AFM have been manifested upon cooling in kagome FeGe. However, the mechanism of CDW and interaction with magnetism remains unclear. Here we investigate the evolution of CDW with temperature across the canted AFM by single-crystal x-ray diffraction, scanning tunneling microscope (STM) and resonant elastic x-ray scattering (REXS). For the samples with longer annealing periods, CDW-induced superlattice reflections become weak after the canted AFM transition, although long-range CDW order is still detectable by STM and REXS. We explore a long-range CDW order with suppressed structural modulation. Additionally, occupational modulations of Ge1 in the kagome plane and displacive modulations of all atoms were extracted. The results confirm Ge dimerization along the c axis and suggest a dynamic transformation between different CDW domains. Kagome materials have become a popular platform to investigate a range of competing quantum phases, such as the interplay between superconductivity and charge density waves (CDW). Here, the authors use x-ray diffraction, scanning tunneling microscopy and resonant elastic x-ray scattering to investigate the evolution of CDW ordering as a function of temperature in canted antiferromagnetic kagome FeGe. They find for post-annealed samples that the long-range CDW orders persist even as the structural modulations are suppressed although observations are highly dependent on the sample growth condition.

Superconductivity involving finite-momentum pairing 1 can lead to spatial-gap and pair-density modulations, as well as Bogoliubov Fermi states within the superconducting gap. However, the experimental realization of their intertwined relations has been challenging. Here we detect chiral kagome superconductivity modulations with residual Fermi arcs in KV 3 Sb 5 and CsV 3 Sb 5 using normal and Josephson scanning tunnelling microscopy down to 30 millikelvin with a resolved electronic energy difference at the microelectronvolt level. We observe a U-shaped superconducting gap with flat residual in-gap states. This gap shows chiral 2 a  × 2 a spatial modulations with magnetic-field-tunable chirality, which align with the chiral 2 a ×  2 a pair-density modulations observed through Josephson tunnelling. These findings demonstrate a chiral pair density wave (PDW) that breaks time-reversal symmetry. Quasiparticle interference imaging of the in-gap zero-energy states reveals segmented arcs, with high-temperature data linking them to parts of the reconstructed vanadium d -orbital states within the charge order. The detected residual Fermi arcs can be explained by the partial suppression of these d -orbital states through an interorbital 2 a ×  2 a PDW and thus serve as candidate Bogoliubov Fermi states. In addition, we differentiate the observed PDW order from impurity-induced gap modulations. Our observations not only uncover a chiral PDW order with orbital selectivity but also show the fundamental space–momentum correspondence inherent in finite-momentum-paired superconductivity. Using normal and Josephson scanning tunnelling microscopy, chiral kagome superconductivity modulations with corresponding residual Fermi arcs are detected in KV 3 Sb 5 and CsV 3 Sb 5 .

Superconductivity and magnetism are often antagonistic in quantum matter, although their intertwining has long been considered in frustrated-lattice systems. Here we utilize scanning tunnelling microscopy and muon spin resonance to demonstrate time-reversal symmetry-breaking superconductivity in kagome metal Cs(V, Ta) 3 Sb 5 , where the Cooper pairing exhibits magnetism and is modulated by it. In the magnetic channel, we observe spontaneous internal magnetism in a fully gapped superconducting state. Under the perturbation of inverse magnetic fields, we detect a time-reversal asymmetrical interference of Bogoliubov quasi-particles at a circular vector. At this vector, the pairing gap spontaneously modulates, which is distinct from pair density waves occurring at a point vector and consistent with the theoretical proposal of an unusual interference effect under time-reversal symmetry breaking. The correlation between internal magnetism, Bogoliubov quasi-particles and pairing modulation provides a chain of experimental indications for time-reversal symmetry-breaking kagome superconductivity. The authors use scanning tunnelling microscopy and muon spin resonance to demonstrate time-reversal symmetry-breaking superconductivity in Cs(V, Ta) 3 Sb 5 . The Cooper pairing in this state exhibits magnetism and is modulated by it.

Abstract Background Chronic insomnia disorder (CID) is associated with disrupted functional brain networks, yet prior research has focused primarily on group-level analyses. This study employed personalized functional network mapping to identify connectivity abnormalities in CID. Methods Resting-state functional magentic resonance imaging (rs-fMRI) data were collected from 86 CID patients and 38 good sleeper controls (GSCs). Using non-negative matrix factorization (NMF), we derived individualized large-scale brain networks for each participant to uncover subject-specific connectivity changes in CID. We also constructed functional network connectivity (FNC) matrices using Pearson correlation coefficients and compared global and local graph-theory metrics across groups based on these individualized networks. Results FNC analysis revealed significant differences between CID patients and GSCs within the default mode network (DMN), ventral attention network, visual network (VIS), and other key brain regions. CID exhibited altered global network topology and significant differences in local topological properties. At the global level, CID demonstrated significantly higher small-worldness (Sigma) and normalized clustering coefficient (Gamma). At the nodal level, CID showed increased local efficiency and clustering coefficient, as well as decreased nodal efficiency in the DMN, along with increased degree centrality in the VIS. Conclusion By focusing on individualized functional connectivity, this approach reveals unique “fingerprint” alterations in CID. These findings provide novel insights into CID’s neurobiological mechanisms and underscore the value of personalized network approaches for understanding and treating sleep disorders.

Topological quantum materials with kagome lattices have attracted intense interest due to their unconventional electronic structures, which exhibit nontrivial topology, anomalous magnetism, and electronic correlations. Among these, Co 3 Sn 2 S 2 stands out as a prototypical kagome metal, uniquely combining intrinsic ferromagnetism with topologically nontrivial electronic states. This perspective presents a systematic overview of recent advances in studying kagome metal Co 3 Sn 2 S 2 achieved through scanning tunneling microscopy. We begin by introducing different methodologies for surface identification and propose using designer layer-selective chemical markers for conclusive surface identification. We then discuss the Berry curvature induced flat band orbital magnetism and the associated unconventional Zeeman effect. Furthermore, we explore boundary states arising from Weyl topology and analyze challenges in detecting Fermi arcs via quasiparticle interference patterns and in uncovering the topological aspect of the edge states. Finally, we review recent observations of spin-orbit-coupled quantum impurity states through spin-polarized tunneling spectroscopy, as well as their connection to Weyl topology and flat band magnetism. We also provide in-depth analysis and constructive comments on the limitations of the current research approach. This review highlights the critical role of scanning tunneling microscopy in unraveling the intricate interplay between topology, magnetism, and correlations at the atomic scale, and the methodology discussed here can be applied to study other topological quantum materials in general.