Phys. Rev. Lett. 133, 046503 (2024) The kagome spin ice can host frustrated magnetic excitations by flipping its
local spin. Under an inelastic tunneling condition, the tip in a scanning
tunneling ...microscope can flip the local spin, and we apply this technique to
kagome metal HoAgGe with a long-range ordered spin ice ground state. Away from
defects, we discover a pair of pronounced dips in the local tunneling spectrum
at symmetrical bias voltages with negative intensity values, serving as a
striking inelastic tunneling signal. This signal disappears above the spin ice
formation temperature and has a dependence on the magnetic fields,
demonstrating its intimate relation with the spin ice magnetism. We provide a
two-level spin-flip model to explain the tunneling dips considering the spin
ice magnetism under spin-orbit coupling. Our results uncover a local emergent
excitation of spin ice magnetism in a kagome metal, suggesting that local
electrical field induced spin flip climbs over a barrier caused by spin-orbital
locking.
The bulk boundary correspondence in the context of Weyl semimetals is a fundamental topological principle that establishes a connection between the bulk properties of the material and the emergence ...of specific surface states. In Weyl semimetals, the bulk boundary correspondence is manifested by the presence of surface Fermi arcs connecting pairs of Weyl nodes with opposite chirality. Here we demonstrate that this bulk boundary correspondence is challenged in the case of the surface selectively reconstructed noncentrosymmetric magnetic Weyl semimetal NdAlSi. By comparing angle-resolved photoemission spectroscopy measurements with surface projected density functional theory calculations and scanning tunneling microscope measurements, the existence of surface selective spontaneous reconstruction is demonstrated. The surface reconstruction in NdAlSi not only leads to the reconstruction of the surface Fermi arcs, but also generates new surface Fermi arcs that do not connect corresponding Weyl nodes. This observation challenges the conventional view of the bulk boundary correspondence in Weyl semimetals.
By using the analyzing method of Grey Relational Entropy, this paper makes specific analysis of the elements which affected. Combined with the status of Shanxi investment environment, we can find the ...primary and secondary order of the specific elements. And it is easy for seeking the channels and countermeasures to enhance Shanxi FDI Absorption Capacity effectively by conducting in-depth analysis.
Nature Communications 14, 2905 (2023) The century-long development of surface sciences has witnessed the
discoveries of a variety of quantum states. In the recently proposed
"obstructed atomic ...insulators", insulators with symmetric charges 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 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 a pair of
surface states originated from the pristine obstructed surface states split 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.
We introduce Eurus, a suite of large language models (LLMs) optimized for reasoning. Finetuned from Mistral-7B and CodeLlama-70B, Eurus models achieve state-of-the-art results among open-source ...models on a diverse set of benchmarks covering mathematics, code generation, and logical reasoning problems. Notably, Eurus-70B beats GPT-3.5 Turbo in reasoning through a comprehensive benchmarking across 12 tests covering five tasks, and achieves a 33.3% pass@1 accuracy on LeetCode and 32.6% on TheoremQA, two challenging benchmarks, substantially outperforming existing open-source models by margins more than 13.3%. The strong performance of Eurus can be primarily attributed to UltraInteract, our newly-curated large-scale, high-quality alignment dataset specifically designed for complex reasoning tasks. UltraInteract can be used in both supervised fine-tuning and preference learning. For each instruction, it includes a preference tree consisting of (1) reasoning chains with diverse planning strategies in a unified format, (2) multi-turn interaction trajectories with the environment and the critique, and (3) pairwise data to facilitate preference learning. UltraInteract allows us to conduct an in-depth exploration of preference learning for reasoning tasks. Our investigation reveals that some well-established preference learning algorithms may be less suitable for reasoning tasks compared to their effectiveness in general conversations. Inspired by this, we derive a novel reward modeling objective which, together with UltraInteract, leads to a strong reward model.
Superconductivity and magnetism are antagonistic quantum matter, while their
intertwining has long been considered in frustrated-lattice systems1-3. In this
work, we utilize scanning tunneling ...microscopy and muon spin resonance to
discover time-reversal symmetry-breaking superconductivity in kagome metal
Cs(V,Ta)3Sb5, where the Cooper pairing exhibits magnetism and is modulated by
it. In the magnetic channel, we observe spontaneous internal magnetism in a
full-gap superconducting state. Under perturbations 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 unusual
interference effect under time-reversal symmetry-breaking. The correlation
between internal magnetism, Bogoliubov quasi-particles, and pairing modulation
provides a chain of experimental clues for time-reversal symmetry-breaking
kagome superconductivity.
Superconductivity involving finite momentum pairing 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 KV3Sb5 and CsV3Sb5 by normal and
Josephson scanning tunneling microscopy down to 30mK with resolved electronic
energy difference at microelectronvolt level. We observe a U-shaped
superconducting gap with flat residual in-gap states. This gap exhibits chiral
2 by 2 spatial modulations with magnetic field tunable chirality, which align
with the chiral 2 by 2 pair density modulations observed through Josephson
tunneling. 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 V 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 by 2 PDW and thus serve as
candidate Bogoliubov Fermi states. Additionally, 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 illuminate the
fundamental space-momentum correspondence inherent in finite momentum paired
superconductivity.
The performance of human pose estimation depends on the spatial accuracy of keypoint localization. Most existing methods pursue the spatial accuracy through learning the high-resolution (HR) ...representation from input images. By the experimental analysis, we find that the HR representation leads to a sharp increase of computational cost, while the accuracy improvement remains marginal compared with the low-resolution (LR) representation. In this paper, we propose a design paradigm for cost-effective network with LR representation for efficient pose estimation, named FasterPose. Whereas the LR design largely shrinks the model complexity, yet how to effectively train the network with respect to the spatial accuracy is a concomitant challenge. We study the training behavior of FasterPose, and formulate a novel regressive cross-entropy (RCE) loss function for accelerating the convergence and promoting the accuracy. The RCE loss generalizes the ordinary cross-entropy loss from the binary supervision to a continuous range, thus the training of pose estimation network is able to benefit from the sigmoid function. By doing so, the output heatmap can be inferred from the LR features without loss of spatial accuracy, while the computational cost and model size has been significantly reduced. Compared with the previously dominant network of pose estimation, our method reduces 58% of the FLOPs and simultaneously gains 1.3% improvement of accuracy. Extensive experiments show that FasterPose yields promising results on the common benchmarks, i.e., COCO and MPII, consistently validating the effectiveness and efficiency for practical utilization, especially the low-latency and low-energy-budget applications in the non-GPU scenarios.
Strongly correlated electron systems with a kagome lattice can host abundant exotic quantum states such as superconductivity and spin/charge density waves (CDW) due to the complicated interactions ...between different degrees of freedoms in the framework of a unique two-dimensional geometrically frustrated lattice structure. Recently, successive orders of A-type antiferromagnetism (AFM), \(2\times2\times2\) CDW and canted double-cone AFM have been manifested upon cooling in magnetic kagome FeGe. However, the mechanism of the CDW order and its interaction with magnetism are presently enigmatic at best. Here we investigate the evolution of CDW order with temperature across the spin canting transition in FeGe by single-crystal x-ray diffraction. Refinements of its modulated structure are presented using the superspace approach. Interestingly, the superlattice reflections originating from CDW-induced long-range structural modulation become extremely weak after the system enters the canted AFM while a \(2\times2\) CDW in the \(ab\) plane persists as a long-range order demonstrated by strong electronic modulation in the d\(I\)/d\(V\) map of scanning tunneling spectroscopy. We discovered a novel CDW order without long-range structural modulation in FeGe probably because of the competition between CDW and canted AFM in determining the underlying crystal structure. In addition, occupational modulations of Ge1 atoms located in the kagome plane and displacive modulations of all the atoms were extracted from the refinements, confirming the existence of Ge atom dimerization along the \(c\) axis as the major distortion and indicating a dynamic transformation between different CDW domains.
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