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An elliptical camphor-coated paper disk whose center of mass is fixed at the rotational axis rotates spontaneously with a constant angular velocity when placed on the surface of water. In our experiments, we observed bifurcation by controlling the water depth, i.e., the disk rotated and was stationary at higher and lower water depths, respectively. Further, the bifurcation type depended on the aspect ratio of the elliptical camphor disk; subcritical and supercritical bifurcations were observed in the high- and low-aspect-ratio experiments, respectively. Thus, the experiments and phenomenological models indicated that the friction between the acrylic rod as the rotational axis and the center pore of the disk penetrated by the rod determined the bifurcation type. [ABSTRACT FROM AUTHOR]

In systems with charge and orbital degrees of freedom, spontaneous molecular formation phenomena occur at low temperatures as these degrees of freedom become entangled with the lattice. In this paper, we introduce the trimer molecule formation phenomenon in the layered LiVX2 (X = O, S, Se) system, which appears as the ground state at low temperatures, and the development of short-range order in zigzag chains that unexpectedly appears in the pseudogap metallic phase just prior to trimerization. Although a precursory molecular formation can be generally observed in various systems, we will argue that layered LiVX2 has unique structural features that distinguish it from these analogs. [ABSTRACT FROM AUTHOR]

In order to study the mechanism of submicron-scale air gap discharge, the gas discharge experiment with electrode gap of 0.3-10 um was carried out by using nano-positioning system under atmospheric pressure. The breakdown voltages of stainless steel, brass, copper, and aluminum electrodes were measured. The experimental results are obviously deviated from the Paschen curve, and the Paschen curve cannot explain the air gap breakdown voltage. It is found that in the range of 0.3-5 um, the material work function significantly affects the air gap breakdown voltage, and it is not obvious in the range of 5-10 um. By studying the breakdown field strength, current density and F-N theory, it is found that when the electrode gap is 0.3-5 um, the field emission is dominant, resulting in the breakdown voltage deviating from the Paschen curve. In addition, the breakdown voltages under different discharge mechanisms are numerically calculated, and the numerical results are compared with the experimental results. The results show that only field emission needs to be considered at the gap of 0.3-2 um, and other discharge mechanisms can be ignored. Through the research of this paper, it provides a basis for the in-depth study of sub-micron electrical breakdown and the design of microelectronic devices. [ABSTRACT FROM AUTHOR]

In this paper, we report on the effect of pressure on the angular-dependent magnetoresistance and Shubnikov–de Haas (SdH) oscillation for β′′-(ET)(TCNQ), where ET and TCNQ stand for bis(ethylenedithio)tetrathiafulvalene and tetracyanoquinodimethane, respectively. At 0 kbar, the temperature dependence of the interlayer resistance shows three hump anomalies at around T1 = 174 K, T2 = 72 K, and T3 = 22 K. At low temperatures below T3, both the Yamaji oscillation and the periodic dip structure due to a commensurability effect are clearly observed in the angular dependence of the interlayer resistance at high magnetic fields. At 2.0 kbar, the T1-anomaly is suppressed and the T2- and T3-anomalies shift to lower temperatures. Below T3, a similar Yamaji oscillation and the dip structure are evident. At 5.1 kbar, the T3-anomaly is removed, and only the dip structure is clearly observed at low temperatures. From this finding, the dip structure is attributable to a commensurability effect between the possible 4kF charge-density wave in the TCNQ layers and the interlayer lattice potential. Although no Yamaji oscillation is observed at 5.1 kbar, a higher SdH frequency than that at 0 kbar is detected, suggesting the emergence of a magnetic breakdown orbit in the significantly undulated Fermi surface originating from the ET layers. The temperature–pressure phase diagram of β′′-(ET)(TCNQ) is determined from the resistance measurements. [ABSTRACT FROM AUTHOR]

The current-driven motion of magnetic skyrmions, as topologically protected winding vector fields of local magnetization, has attracted considerable attention due to both fundamental interest in the dynamics of topological solitons, and potential spintronic applications. While widely-used Thiele equation with zero skyrmion mass captures its rigid motion under the assumption of preserved skyrmion shape, experiments on realistic skyrmions find deviation due to inertial mass with numerous attempts to account for it by invoking internal skyrmion dynamics, geometry of the nanowire, and interaction with magnons or phonons. However, experimentally observed skyrmion mass is often much larger than predicted by these theories. In this paper, we employ Schwinger–Keldysh field-theoretical approach to study conduction electrons interacting with localized magnetic moments comprising a skyrmion to obtain a stochastic differential equation of its motion. By analyzing its time-retarded damping kernel, we extract an anisotropic mass governed by conduction electrons and demonstrate its substantial effect on the current-driven skyrmion motion, even in the absence of any skyrmion deformation. [ABSTRACT FROM AUTHOR]

The Institute for Materials Research at Tohoku University has a long history of neutron research and has contributed to the research community since the beginning of neutron science in Japan. The Center of Neutron Science for Advanced Materials, established in 2010, manages three neutron instruments (powder diffractometer HERMES, high-momentum resolution three-axis spectrometer AKANE, and polarized neutron three-axis spectrometer TOPAN) in Japan Research Reactor JRR-3. These instruments, along with the chopper spectrometer POLANO constructed jointly with the High Energy Accelerator Research Organization at the Materials and Life Science Experimental Facility, are named PATH from the initial characters of each name. In this paper, we introduce the advantages of the PATH platform for neutron beam utilization and present the overview of the two spectrometers at JRR-3, showcasing the possible measurements that can be conducted on these spectrometers. Representative results obtained using the AKANE and TOPAN spectrometers are also presented to promote neutron scattering experiments to general users. Furthermore, we outline our current and future plans for instrument upgrades to advance our research in magnetism, a primary focus of our ongoing and upcoming investigations. [ABSTRACT FROM AUTHOR]

Recently, the two-dimensional (2D) hexagonal network (HexNet) structures have been synthesized based on the hydrogen-bonded buckybowled sheet. The remarkable feature of 2D HexNet system has a double-decker structure, where two lattice networks are mutually woven. In this paper, we shall focus on exploring the electronic and topological properties of the 2D HexNet system. In the conventional HexNet system, each molecule forms hydrogen bonds with six neighboring molecules, allowing for an approximation of 2D HexNet as a double-decker 2D tight-binding network with six coordination (HexNet-6). This configuration exhibits characteristics of a nodal line semimetal, explained by parity analysis in momentum space. In contrast, the HexNet with a three-coordinate structure (HexNet-3), presents six Dirac points and a nontrivial Zak phase of π, leading to the emergence of topological edge states, shedding light on its unique electronic behavior. [ABSTRACT FROM AUTHOR]

The main interest of the present paper is to discuss fundamental probabilistic graphical models that have only spatially uniform interactions on random regular graphs (Bethe lattice) and show a complex scenario with both second-order and first-order phase transitions. To clarify the mechanism underlying this complex scenario, we study the internal energy, the susceptibility, and the order parameters in the Generalized Sparse Gaussian Graphical Model on the Bethe Lattice with degree 4. [ABSTRACT FROM AUTHOR]

In recent years, machine learning leveraging neural networks has emerged as a potent tool across various domains, including natural language processing, image recognition, game strategy optimization, and even addressing challenges in physics. Although there are many studies on the application of machine learning to the numerical calculation and assistance of experiments, the methods of applying machine learning to developing the analytical method are poorly studied. In this paper, we propose the frameworks for developing analytical methods in physics by using the symbolic regression with the Alpha Zero algorithm, that is, Alpha Zero for Physics (AZfP). As a demonstration, we show that AZfP can derive the high-frequency expansion in the Floquet systems. This result suggests that AZfP is applicable developing a new theoretical framework in physics. [ABSTRACT FROM AUTHOR]

Environmental noises cause quantum systems to relax, which can significantly impact the precision of operations. Grasping the relaxation mechanism caused by environmental noises is a crucial step in the development of quantum technologies. Relaxations can be viewed as a process of information dissipation from the system into an environment with infinite degrees of freedom (DoF). This concept has led to the proposal and demonstration of a model of artificial relaxation in NMR experiments. While the current model has successfully captured the central idea of relaxation, we have observed recursive behavior due to the limited DoF of the "artificial environment". This limitation hampers its ability to describe relaxation accurately. This paper aims to overcome this limitation by extending the approach and studying the relaxation-like behavior through manipulating DoF. Our study promises to provide a more comprehensive understanding of the concept of relaxation. [ABSTRACT FROM AUTHOR]

Link prediction plays an important role in network analysis and can be applied to many applications, including marketing analysis and information retrieval. However, for privacy reasons, we may want to prevent future links from being predicted in certain cases. In this paper, we propose a novel attack method called adopted differential evolution (ADE). From the attacker's perspective, ADE aims to maximally disperse a group of neighbor nodes to evade prediction. We transform the attack problem into a combinatorial optimization problem and generate well-designed perturbations using differential evolution. We present attacks for four matrix-based temporal link prediction methods. Numerical experiments demonstrate that the ADE can successfully attack temporal link prediction algorithms by slightly modifying network structure. By comparison, our method outperforms both random attacks and communicability-based attacks on real-world networks. Moreover, the proposed perturbation generated by ADE is transferable and it is also effective in attacking other similarity-based link prediction methods. [ABSTRACT FROM AUTHOR]