We obtain the ground-state phase diagram of the S = 1 Kitaev-Γ model on a bond-anisotropic honeycomb lattice using exact diagonalization, density-matrix renormalization group, and infinite time-evolving block decimation. The Tomonaga–Luttinger liquid region of the S = 1/2 model is replaced by a Haldane-gap phase at d = 0 that appears to extend into a Haldane-gap-like region for finite d. The bond-isotropic line d = 1 shows finite-size phase-boundary signatures over an extended range.
In studies of the promising topological Kondo insulator (TKI) candidate SmB 6 , nuclear magnetic resonance (NMR) measurements of the spin–lattice relaxation rate, 1/T 1 , have provided crucial insights into this compound: for example, the unique opening of a small hybridization gap within a narrow band at low temperatures. However, the origin of the hump-like behavior of 1/T 1 reported below 20 K remains poorly understood. To address the mechanisms of low-temperature T 1 relaxation, we have precisely analyzed the 11 B-NMR T 1 relaxation curves of single-crystalline SmB 6 by introducing a Bayesian inference framework, which provides insights beyond the conventional least-squares fit in terms of a quantitative measure of fitting quality. Our comparative analysis using three different models reveals that the T 1 relaxation curve, which is well described by a single component above ∼100 K, evolves into a multi-component regime below ∼60 K, suggesting the inhomogeneous development of the hybridization gap. Below ∼20 K, 1/T 1 in the present study also exhibits an anomalous enhancement, which remains clear even after considering the distribution of T 1 components. The analysis suggests that this low-temperature enhancement is an intrinsic property of this compound, and that a novel relaxation mechanism — distinct from the high-temperature process driven by the density of states — emerges in this temperature region. These observed phenomena are discussed based on the analogy with other potential TKIs, SmS, and YbB 12 .
Helical laminates, in which fibrous elements are stacked while rotating by a constant angle from one layer to the next, are common in natural and artificial materials, including Bouligand structures and fiber-reinforced composites. This study clarifies the geometric pitch-angle conditions that allow axially symmetric rod-like elements with periodic surface corrugations to form helical laminations. Using a rod model based on rods with axially symmetric periodic corrugations, we derive the stackability conditions under which the same stacking pattern can be repeated while maintaining concavity-to-concavity contact between adjacent layers. We show that the allowed intralayer phase shift is restricted to either zero or half the axial period and that the admissible pitch angles form discrete series determined by integer parameters. Mesh-based collision detection and rigid-body simulations confirm that these conditions predict stackable configurations for realistic rod shapes and that smaller pitch angles are mechanically more unstable.
A minimal theory of nonradiative energy transfer from a two-dimensional (2D) moiré exciton to a nearby graphene layer is presented. From Fermi’s golden rule the transfer rate is the overlap of the exciton near-field spectrum with the dissipative density response of graphene, weighted by an exciton form factor, and it reproduces the established Γ ET ∝ [Formula: see text] −4 law in the point-dipole limit. A finite exciton size filters out the high-momentum near field once the spacer thickness approaches the transition-polarization radius R X , so the distance dependence of the rate — and of the photoluminescence (PL) quenching — probes the exciton size. A low-momentum expansion shows that, relative to the calibrated point-dipole response of the same bath, this leading correction is set by R X alone. In the ideal coherent-envelope limit the accompanying giant oscillator strength makes the rate non-monotonic in the exciton size, with a peak near [Formula: see text]. Treating graphene as a gate-tunable bath, Pauli blocking suppresses the interband channel once 2|μ F | approaches ħω, partially restoring PL, and a full random-phase-approximation benchmark confirms the normalized interband distance dependence to within a few percent away from the threshold. Mapping the PL observables across the transition-metal dichalcogenide/hexagonal boron nitride/graphene parameter space, we find that a graphene gate acts not as a passive electrostatic element but as a tunable 2D electronic reservoir probed through exciton PL quenching.
Markov chain Monte Carlo algorithms can be viewed as feedback devices that compare a proposed move with the target distribution and then accept or reject it. In this paper the Maxwell demon is identified with the acceptance module: it measures a proposed edge, stores the outcome in the accept/reject bit, and uses that bit to shape the probability current. The decision bit carries a genuine Shannon mutual information about the proposal, whereas only its directional part is converted into a cooling information flow. The relative-entropy relaxation rate obeys v(t)=ℐ̇_ cool(t)+Ṡ(t), which separates useful cooling from housekeeping circulation in nonreversible chains.
To investigate the influence of electrode surface roughness on gas discharge characteristics under micro-gap conditions, direct-current breakdown experiments were carried out in atmospheric air using a nano-positioning system. Breakdown tests were conducted for five metal electrodes over the electrode gap distances from 1 to 10 µm, and for one metal with different surface roughness levels over the electrode gap distances from 1 to 20 µm. Meanwhile, the electric field intensity distribution of aluminum electrodes (cathode) with different surface roughness values was simulated using Maxwell electromagnetic field simulation software. The experimental results show that, in the electrode gap distances from 1 to 5 µm, different metal electrodes exhibit different degrees of deviation from the Paschen curve, all of which are related to the work function. At the same electrode gap distance, the rougher the electrode surface, the larger the field enhancement factor β and the lower the breakdown voltage. Analysis indicates that surface protrusions cause local electric field intensification, allowing the field strength to reach the critical condition for field electron emission, thereby reducing the breakdown voltage. In the electrode gap distances from 10 to 20 µm, electrode surface roughness leads to a multiplication of the effective electron emission from the cathode surface, thus enhancing the surface electron emission process. Therefore, in the design of microelectronic devices, reducing electrode surface roughness and selecting metal electrode materials with higher work functions can effectively improve gas breakdown characteristics under small-gap conditions and optimize the insulation protection of microelectronic devices.
The study of electronic orbital degrees of freedom, including the generation and control of orbital currents and orbital angular momentum, has emerged as a vibrant research field. Here, we study the orbital Hall effect (OHE), one of the key mechanisms for orbital current generation, in transition-metal kagome-lattice metals. We propose a large positive OHE in CsTi_3Bi_5 and negative OHEs in CsV_3Sb_5 and CsCr_3Sb_5 models. Orbital-sector decomposition shows that the | l^z_d |=2 d-orbital channel gives a positive contribution, whereas the | l^z |=1 d- and p-orbital channels can give negative contributions. Control calculations suggest a persistent orbital-sector sign tendency near the actual filling, while strong p-d hybridization modulates the quantitative balance and total OHE sign. Thus, the compound and filling dependence of the OHE reflects both the sign tendency of each orbital sector and the hybridization-controlled balance among them. Furthermore, we investigate the loop-current phase of CsV_3Sb_5 and show that it induces finite local atomic orbital angular momentum. We also show that loop-current-related symmetry lowering allows finite symmetric components of the orbital conductivity tensor. This study provides a basis for exploring orbital currents and local orbital-angular-momentum responses in strongly correlated kagome metals.
In this study, based on the crest line model, a differential equation-based mathematical approach to dune dynamics, we investigate the effect of non-contact interactions between barchans through sand flow on their morphodynamics, which is a largely unexplored topic. Numerical calculations reveal the following: (i) When sand flows into a single point along the upwind slope of a barchan, the central axis aligns with the sand inflow point. Consequently, the profile of the barchan develops a sharper, pointed steady shape in the front view and a slightly deformed parabola in the top view. (ii) When sand flows into two points, the initial barchan splits into two. This division depends on the inflow amount and distance between the sand influx points. In addition, under a one-point sand inflow, the analytical solution supports the numerical results and provides an explicit mathematical expression of the crest line in the steady states. These results provide new insights into the spatio-temporal dynamics of barchans in desert areas with active interdune sand flows and further our understanding of the complex dynamics of barchan collisions.
We investigate the electronic structure of TaS 2 in the so-called misfit compound (SnS) 1.15 (TaS 2 ) by angle-resolved photoemission spectroscopy. Our results reveal that in contrast to 2H-TaS 2 , TaS 2 layer in (SnS) 1.15 (TaS 2 ) does not exhibit a three-dimensional character: it behaves as a relatively electronically isolated unit with an effective spin–orbit coupling. We find the band shifts near the Fermi level and very weak dispersion along the k[Formula: see text] direction. SnS-derived electronic states below the Fermi level reflect the structural flexibility of the SnS layer, suggesting that an unconventional covalent bonding plays a role in the crystal stability of (SnS) 1.15 (TaS 2 ).
The crystal structure of β-phase Pb x V 2 O 5 without superlattice reflection at x < 0.29 and the superlattice structure without diffuse scattering at 0.29 ≤ x ≤ 0.33 are precisely determined for x = 0.28 [analytical value = 0.2662(8)] and 0.33 [0.324(2)], respectively, indicating that the superlattice arises mainly from the partial ordering of Pb ions in the tunnels of the V 2 O 5 framework. The model for the two types of one-dimensional spin chains attached to the V–O–V molecular orbitals, where all V ions are in a mixed-valence state, is valid regardless of the presence or absence of Pb ion ordering. Long-time annealing of the crystal may induce short-range order between Pb ion layers only at x = 0.33, leading to the electron localization regarding transport and magnetic properties. The transport properties of x = 0.20 may be hopping conduction, those of 0.25 ≤ x ≤ 0.30 and the short-time annealed x = 0.33 have metallic phase, and those of long-time annealed x = 0.33 are nonmetallic. The composition dependence of thermoelectric power is explained with the spin chain model in the high-temperature limit. At x = 0.33, in the case of short-time annealing, only one of the two types of chains exhibits antiferromagnetic uniform chain magnetism with a nearly infinite chain length, whereas in the case of long-time annealing, both chains indicate the uniform chain magnetism.
We report single-shot terahertz time-domain spectroscopy of Cr_2O_3 in pulsed magnetic fields up to 30 T. Well above the spin-flop field, in the 20-30 T range, the resonance frequency exhibits a nearly linear field dependence with a slope of 22 GHz/T, smaller than the 28 GHz/T reported from low-field measurements. This reduction is insensitive to temperature and to a 15° field tilt, suggesting an intrinsic high-field property.
