Lattice Effects Research Articles

Effective spin dynamics of spin-orbit coupled matter-wave solitons in optical lattices

We consider matter–wave solitons in spin–orbit coupled Bose–Einstein condensates embedded in an optical lattice and study the dynamics of the soliton within the framework of Gross–Pitaevskii equations. We express spin components of the soliton pair in terms of nonlinear Bloch equations and investigate the effective spin dynamics. It is seen that the effective magnetic field that appears in the Bloch equation is affected by optical lattices, and thus the optical lattice influences the precessional frequency of the spin components. We make use of numerical approaches to investigate the dynamical behavior of density profiles and center-of-mass of the soliton pair in the presence of the optical lattice. It is shown that the spin density is periodically varying due to flipping of spinors between the two states. The amplitude of spin-flipping oscillation increases with lattice strength. We find that the system can also exhibit interesting nonlinear behavior for chosen values of parameters. We present a fixed point analysis to study the effects of optical lattices on the nonlinear dynamics of the spin components. It is seen that the optical lattice can act as a control parameter to change the dynamical behavior of the spin components from periodic to chaotic.

Fractional Chern Insulators in Twisted Bilayer MoTe_{2}: A Composite Fermion Perspective.

The discovery of fractional Chern insulators (FCIs) in twisted bilayer MoTe_{2} has sparked significant interest in fractional topological matter without external magnetic fields. Unlike the flat dispersion of Landau levels, moiré electronic states are influenced by lattice effects within a nanometer-scale superlattice. This Letter examines the impact of these lattice effects on the topological phases in twisted bilayer MoTe_{2}, uncovering a family of FCIs with Abelian anyonic quasiparticles. Using a composite fermion approach, we identify a sequence of FCIs with fractional Hall conductivities σ_{xy}=[C/(2C+1)](e^{2}/h) linked to partial filling ν_{h} of holes of the topmost moiré valence band. These states emerge from incompressible composite fermion bands of Chern number C within a complex Hofstadter spectrum. This approach explains FCIs with Hall conductivities σ_{xy}=(2/3)e^{2}/h and σ_{xy}=(3/5)e^{2}/h at fractional fillings ν_{h}=2/3 and ν_{h}=3/5 observed in experiments, and uncovers other fractal FCI states. The Hofstadter spectrum reveals new phenomena, distinct from Landau levels, including a higher-order Van Hove singularity (HOVHS) at half-filling, leading to novel quantum phase transitions. This Letter offers a comprehensive framework for understanding FCIs in transition metal dichalcogenide moiré systems and highlights mechanisms for topological quantum criticality.

Tracking intrinsic non-Hermitian skin effects in lossy lattices

Tracking intrinsic non-Hermitian skin effects in lossy lattices

Lattice distortion effects in high-entropy oxides: Boosting PMS activation for effective and durable pollutant degradation

Advanced Oxidation Processes (AOPs) are highly effective for pollutant removal, but achieving an optimal combination of high reactivity, corrosion resistance, and long-term stability remains challenging. In this study, we present the synthesis of a distinctive hollow prismatic high-entropy oxide, (Co0.2Ni0.2Mn0.2Cu0.2Zn0.2)3O4, derived from complex coordination polymers. This high-entropy oxide exhibits significant lattice distortion effects compared to conventional (Co1/3Ni1/3Mn1/3)3O4 and Co3O4. These distortions reduce the metal-O bond length, which enhances cyclic stability during peroxymonosulfate (PMS) activation for pollutant degradation. Additionally, the improved interaction between the catalyst and PMS enhances the generation of reactive oxygen species (ROS), leading to superior catalytic degradation activity. Electron paramagnetic resonance (EPR) and other analytical techniques identify ·OH, 1O2, O2−· as the primary active species in the (Co0.2Ni0.2Mn0.2Cu0.2Zn0.2)3O4/PMS system. A degradation mechanism for tetracycline (TC) is also proposed. This study introduces an innovative approach to water treatment by employing high-entropy oxides to activate PMS, demonstrating substantial potential for practical applications.

Global spectrum model of discrete dislocation equation

The fully discrete dislocation equation can be rationally derived from the spectrum model. In this paper, the previous spectrum model is reinterpreted to cover the global feature of the spectrum. Instead of the local behavior around the origin of the Brilouin zone, the global spectrum model focuses the maximum at the boundary of the Brillouin as well as the slope at the origin of the Brilouin zone. The strength of the point-contact interaction that effectively describes the discreteness effect becomes larger because the whole lattice effect is included in the global spectrum model. The validness and signification of the new model are illustrated by a solvable lattice dynamical model of the cubic lattice.

Nernst effect of the dice lattice in a strong magnetic field

The dice lattice bears a similar honeycomb lattice structure to graphene but with a non-dispersive flat band intersecting the Dirac bands at the band center. In this work, we investigate Nernst effect of the dice lattice in a strong magnetic field, focusing on the role of the flat band. By using the Chebyshev polynomial Green’s function method, we show that no Nernst effect (Sxy=0) is around the Dirac point in the clean limit contrary to the graphene case because of the existence of a zero Hall conductivity platform. However, an unconventional negative Sxy of the double-peak structure emerges instead when the flat band is broadened by disorder and temperature. In addition, when a mass term of Dirac electrons is introduced in the system to open an energy gap, a negative single peak of Sxy appears at the Dirac point and this is due to the derivative quantum Hall effect of non-Dirac electrons in the flat band appearing in the energy gap.

Random field site inequality for ergodicity modification in BNT-based materials: From a phenomenological view

Achieving a simplified BNT-based composition with giant strain properties is challenging, since traditional chemical substitutions rely on trial-and-error experiments and complicates the composition. Herein, we comprehend the strain regulation mechanism from a view of relaxors and propose strain regulation rules based on classical relaxor theory. In BNT-based systems, site inequality of the random field for the ergodicity modification is observed, arising from the discrepant random field-driven (e.g., intensity and action position) structural distortions. From a phenomenological view, B-site substitution is effective in regulating relaxation behaviors due to the stronger lattice softening effect. This work points out the essence of regulating strain properties in BNT-based systems, and the proposed phenomenological relaxation regulation rules are believed to advance the development of actuator applications.

Mechanical properties and biological behavior of refractory TiZrNbTa medium-entropy and TiZrHfNbTa high-entropy alloy nanofilms on AISI 316L for bone implants

To investigate the feasibility of high-entropy alloys as the coating materials for the application of bone implants, TiZrNbTa refractory medium-entropy alloy (RMEA) and TiZrHfNbTa refractory high-entropy alloy (RHEA) nanofilms were prepared on AISI 316L stainless steel by DC magnetron sputtering and post-annealing treatment. Then, the microstructure, mechanical properties, wear resistance, corrosion resistance, biocompatibility and osteogenic activity of the nanofilms were systematically studied. The results showed that both the films exhibited uniform and dense nanostructures. Post-annealing treatment not only improved the adhesion strength, but also formed an oxidized layer. Notably, owing to the enhanced high-entropy and lattice distortion effects, the RHEA nanofilm showed finer grain sizes, higher hardness (14 GPa), H/E, H3/E2 and better wear resistance. The in vitro experiments proved that RHEA nanofilm had the highest Ecorr (−0.127 V), with the Icorr value was two orders of magnitude lower than substrate. Its osteoblast proliferative capacity was 1.5 times higher than substrate (after culturing for 5 days), and the collagen secretion and extracellular matrix mineralization reached an optimal level, showing excellent osteogenic activity. Therefore, RHEA nanofilm coated biomaterials can be a more attractive candidate for bone replacement.

Compressing the two-particle Green’s function using wavelets: Theory and application to the Hubbard atom

Precise algorithms capable of providing controlled solutions in the presence of strong interactions are transforming the landscape of quantum many-body physics. Particularly, exciting breakthroughs are enabling the computation of non-zero temperature correlation functions. However, computational challenges arise due to constraints in resources and memory limitations, especially in scenarios involving complex Green’s functions and lattice effects. Leveraging the principles of signal processing and data compression, this paper explores the wavelet decomposition as a versatile and efficient method for obtaining compact and resource-efficient representations of the many-body theory of interacting systems. The effectiveness of the wavelet decomposition is illustrated through its application to the representation of generalized susceptibilities and self-energies in a prototypical interacting fermionic system, namely the Hubbard model at half-filling in its atomic limit. These results are the first proof-of-principle application of the wavelet compression within the realm of many-body physics and demonstrate the potential of this wavelet-based compression scheme for understanding the physics of correlated electron systems.

Custom Shoe Sole Design and Modeling Toward 3D Printing.

This study introduces a design procedure for improving an individual’s footwear comfort with body weight index and activity requirements by customized three-dimensional (3D)-printed shoe midsole lattice structure. This method guides the selection of customized 3D-printed fabrications incorporating both physical and geometrical properties that meet user demands. The analysis of the lattice effects on minimizing the stress on plantar pressure was performed by initially creating various shoe midsole lattice structures designed. An appropriate common 3D printable material was selected along with validating its viscoelastic properties using finite element analysis. The lattice structure designs were analyzed under various loading conditions to investigate the suitability of the method in fabricating a customized 3D-printed shoe midsole based on the individual’s specifications using a single material with minimum cost, time, and material use.

Interfacial Charge-Transfer Excitonic Insulator in a Two-Dimensional Organic-Inorganic Superlattice.

Excitonic insulators are long-sought-after quantum materials predicted to spontaneously open a gap by the Bose condensation of bound electron-hole pairs, namely, excitons, in their ground state. Since the theoretical conjecture, extensive efforts have been devoted to pursuing excitonic insulator platforms for exploring macroscopic quantum phenomena in real materials. Reliable evidence of excitonic character has been obtained in layered chalcogenides as promising candidates. However, owing to the interference of intrinsic lattice instabilities, it is still debatable whether those features, such as the charge density wave and gap opening, are primarily driven by the excitonic effect or by the lattice transition. Herein, we develop an intercalation chemistry strategy for obtaining a novel charge-transfer excitonic insulator in organic-inorganic superlattice interfaces that serves as an ideal platform to decouple the excitonic effect from the lattice effect. In this system, we observe a narrow excitonic gap, formation of a charge density wave without periodic lattice distortion, and metal-insulator transition, providing visualized evidence of exciton condensation occurring in thermal equilibrium. Our findings identify self-assembly intercalation chemistry as a new strategy for developing novel excitonic insulators.

De Novo Glycan Display on Cell Surfaces Using HaloTag: Visualizing the Effect of the Galectin Lattice on the Lateral Diffusion and Extracellular Vesicle Loading of Glycosylated Membrane Proteins.

Glycans cover the cell surface to form the glycocalyx, which governs a myriad of biological phenomena. However, understanding and regulating glycan functions is extremely challenging due to the large number of heterogeneous glycans that engage in intricate interaction networks with diverse biomolecules. Glycocalyx-editing techniques offer potent tools to probe their functions. In this study, we devised a HaloTag-based technique for glycan manipulation, which enables the introduction of chemically synthesized glycans onto a specific protein (protein of interest, POI) and concurrently incorporates fluorescent units to attach homogeneous, well-defined glycans to the fluorescence-labeled POIs. Leveraging this HaloTag-based glycan-display system, we investigated the influence of the interactions between Gal-3 and various N-glycans on protein dynamics. Our analyses revealed that glycosylation modulates the lateral diffusion of the membrane proteins in a structure-dependent manner through interaction with Gal-3, particularly in the context of the Gal-3-induced formation of the glycan network (galectin lattice). Furthermore, N-glycan attachment was also revealed to have a significant impact on the extracellular vesicle-loading of membrane proteins. Notably, our POI-specific glycan introduction does not disrupt intact glycan structures, thereby enabling a functional analysis of glycans in the presence of native glycan networks. This approach complements conventional glycan-editing methods and provides a means for uncovering the molecular underpinnings of glycan functions on the cell surface.

Study on rotary bending fatigue performance of TC4 lattice structure fabricated by selective laser melting

Prediction of the fatigue performance of lattice structures in additive manufacturing still lacks widely applicable methods. To address this issue, we investigated the effect of a BCC lattice structure combined with thin walls and ribs on the fatigue performance of TC4 alloy samples. The lattice-structured samples were fabricated by selective laser melting. In addition, we proposed a prediction model of fatigue performance that combined ABAQUS finite element analysis with FE-safe fatigue analysis. The simulation and experimental results verified the reliability of the model. Based on this method, the effects of lattice and ribbed plate structures on the bending fatigue performance were investigated. The experimental results showed that the stress concentration generated by lattice structures weakened the fatigue performance. On the contrary, ribbed plates can enhance fatigue performance, which also depends on the orientation of the rib structure. The simulation results showed that increasing the volume fraction of unit cells can mitigate the stress concentration, leading to improved fatigue performance. The lattice structure combined with the rib structure exhibited superior fatigue performance. In addition, the proposed models can also be applied to other metallic materials. The findings in this study can provide a theoretical basis for the design of lattice structures with better fatigue performance.

Co and Ni Ratio Modulation‐Derived Electron Deficient Pd Trimetallic Catalysts for Enhanced Formic Acid Electrooxidation

AbstractPdCoNi trimetallic catalysts attracted extensive interest in direct formic acid fuel cells due to high poisoning resistance and high activity for formic acid electro‐oxidation (FAO). Herein, a series of Pd0.75CoxNiy/C alloys with a modulated ratio of Co and Ni are synthesized to investigate the effect of Co and Ni content on the electronic structure of Pd for FAO. The physical analysis demonstrated that the introduction of Co and Ni induces the lattice strain effect compared to monometallic Pd catalysts. As a consequence of fixing the total amount of Co and Ni, the strain effect is restricted, and the electronic perturbation of Pd is successfully regulated by varying the ratio of Co and Ni in Pd0.75CoxNiy/C trimetallic alloys. Pd loses more electrons, the bond strength of Pd−H is weakened, and FAO activity is enhanced first and then decreased as the Co content increases. Among the trimetallic catalysts, Pd0.75Co0.125Ni0.125/C trimetallic catalyst exhibits the highest current density of 3.253 mA cm−2 owing to the optimum electronic perturbation and Pd−H bond strength. This work provides a valuable guideline for future studies of Pd‐based trimetallic alloys.

Three-dimensional lattice Boltzmann model with self-tuning equationof state for multiphase flows.

In this work, the recent lattice Boltzmann (LB) model with self-tuning equationof state (EOS) [Huang et al., Phys. Rev. E 99, 023303 (2019)2470-004510.1103/PhysRevE.99.023303] is extended to three dimensions for the simulation of multiphase flows, which is based on the standard three-dimensional 27-velocity lattice and multiple-relaxation-time collision operator. To achieve the self-tuning EOS, the equilibrium moment is devised by introducing a built-in variable, and the collision matrix is improved by introducing some velocity-dependent nondiagonal elements. Meanwhile, the additional cubic terms of velocity in recovering the Newtonian viscous stress are eliminated to enhance the numerical accuracy. For modeling multiphase flows, an attractive pairwise interaction force is introduced to mimic the long-range molecular interaction, and a consistent scheme is proposed to compensate for the ɛ^{3}-order discrete lattice effect. Thermodynamic consistency in a strict sense is established for the multiphase LB model with self-tuning EOS, and the wetting condition is also treated in a thermodynamically consistent manner. As a result, the contact angle, surface tension, and interface thickness can be independently adjusted in the present theoretical framework. Numerical tests are first performed to validate the multiphase LB model with self-tuning EOS and the theoretical analyses of bulk and surface thermodynamics. The collision of equal-sized droplets is then simulated to demonstrate the applicability and effectiveness of the present LB model for multiphase flows.

High-Entropy Prussian Blue Analogues Enable Lattice Respiration for Ultrastable Aqueous Aluminum-Ion Batteries.

Aqueous aluminum ion batteries (AAIBs) hold significant potential for grid-scale energy storage owing to their intrinsic safety, high theoretical capacity, and abundance of aluminum. However, the strong electrostatic interactions and delayed charge compensation between high-charge-density aluminum ions and the fixed lattice in conventional cathodes impede the development of high-performance AAIBs. To address this issue, this work introduces, for the first time, high-entropy Prussian blue analogs (HEPBAs) as cathodes in AAIBs with unique lattice tolerance and efficient multipath electron transfer. Benefiting from the intrinsic long-range disorder and robust lattice strain field, HEPBAs enable the manifestation of the lattice respiration effect and minimize lattice volume changes, thereby achieving one of the best long-term stabilities (91.2% capacity retention after 10000 cycles at 5.0 A g-1) in AAIBs. Additionally, the interaction between the diverse metal atoms generates a broadened d-band and reduced degeneracy compared with conventional Prussian blue and its analogs (PBAs), which enhances the electron transfer efficiency with one of the best rate performance (79.2 mAh g-1 at 5.0 A g-1) in AAIBs. Furthermore, exceptional element selectivity in HEPBAs with unique cocktail effect can facile tune electrochemical behavior. Overall, the newly developed HEPBAs with a high-entropy effect exhibit promising solutions for advancing AAIBs and multivalent-ion batteries.

Stabilized Nickel-Rich oxide cathode by the confining effect of Nb lattice anchoring and epitaxial shielding layer

Ni-rich LiNixCoyMn1−x−yO2 cathodes attract growing attention for high energy density but still face great challenges in terms of cyclic lifespan and thermal stability issues. The structural degradation is primarily caused by the increased oxygen vacancy and lattice oxygen loss, especially at high temperatures. Here, we develop an anchoring-confining strategy to rivet lattice oxygen and inhibit the formation and migration of oxygen vacancy by constructing LiNbO3 & LiF epitaxial layer and Nb5+ lattice doping within LiNi0.92Co0.055Mn0.025O2 (NCM92) cathode. The optimized NCM-FN material exhibits excellent stability with retenion of 93 % after 200 cycles at 1C supassing the pristine one (68.7 %), conspicuous high-temperature capacity retention rate (81.6 % vs. 49.5 %) and superior reversible capacity of 165 mAh/g at 5C. In particular, it even possessed superior thermal safety pushing thermal runaway temperature to 223.65 °C. In-situ X-ray diffraction (XRD) result indicates that Nb5+ lattice substitution coupled with LiNbO3 & LiF epitaxial layer alleviates the irreversibility of H2-H3 phase transition, thus stabilizing the layered structure. Furthermore, the LiNbO3 & LiF epitaxial layer, as both a physical shielding layer and ionic conductive layer, protects interface structural integrity and simultaneously promotes Li+ diffusion. X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) results demonstrate that the formation and propagation of oxygen vacancy within NCM-FN material is significantly inhibited. DFT calculation results reveal that Nb5+ introduction can increase the formation energy of oxygen vacancies and inhibit outward migration of active oxygen Oα- (α < 2) to stabilize layer structure by tuning the breaking energy barrier of nearby metal-O bonds. This work not only demonstrates the design of advanced Ni-rich layered cathodes but also underscores the importance of stabilized lattice oxygen for advanced Ni-rich cathodes.

Numerical tests of the large charge expansion

We perform Monte-Carlo measurements of two and three-point functions of charged operators in the critical O(2) model in 3 dimensions. Our results are compatible with the predictions of the large charge superfluid effective field theory. To obtain reliable measurements for large values of the charge, we improved the Worm algorithm and devised a measurement scheme which mitigates the uncertainties due to lattice and finite size effects.

Nucleon form factors in Nf=2+1 lattice QCD at the physical point: Finite lattice spacing effect on the root-mean-square radii

We present results for the nucleon form factors: electric (GE), magnetic (GM), axial (FA), induced pseudoscalar (FP), and pseudoscalar (GP) form factors, using the second PACS10 ensemble that is one of three sets of 2+1 flavor lattice QCD configurations at physical quark masses in large spatial volumes [exceeding (10 fm)3]. The second PACS10 gauge configurations are generated by the PACS Collaboration with the six stout-smeared O(a) improved Wilson quark action and Iwasaki gauge action at the second gauge coupling β=2.00 corresponding to the lattice spacing of a=0.063 fm. We determine the isovector electric, magnetic and axial radii, and magnetic moment from the corresponding form factors, as well as the axial-vector coupling gA. Combining our previous results for the coarser lattice spacing [E. Shintani , ; ], the finite lattice spacing effects on the isovector radii, magnetic moment, and axial-vector coupling are investigated using the difference between the two results. It was found that the effect on gA is kept smaller than the statistical error of 2% while the effect on the isovector radii was observed as a possible discretization error of about 10%, regardless of the channel. We also report the partially conserved axial-vector current relation using a set of nucleon three-point correlation functions in order to verify the effect by O(a) improvement of the axial-vector current. Published by the American Physical Society 2024

High-Entropy Engineering in Thermoelectric Materials: A Review

Thermoelectric (TE) materials play a crucial role in converting energy between heat and electricity, essentially for environmentally friendly renewable energy conversion technologies aimed at addressing the global energy crisis. Significant advances in TE performance have been achieved over the past decades in various TE materials through key approaches, such as nanostructuring, band engineering, and high-entropy engineering. Among them, the design of high-entropy materials has recently emerged as a forefront strategy to achieve significantly low thermal conductivity, attributed to severe lattice distortion and microstructure effects, thereby enhancing the materials’ figure of merit (zT). This review reveals the progress of high-entropy TE materials developed in the past decade. It discusses high-entropy-driven structural stabilization to maintain favorable electrical transport properties, achieving low lattice thermal conductivity, and the impact of high entropy on mechanical properties. Furthermore, the review explores the theoretical development of high-entropy TE material and discusses potential strategies for future advancements in this field through interactions among experimental and theoretical studies.