Physics Letters A最新文献

{"title":"Numerical study of stable and unstable canards in a slow–fast hard-type van der Pol oscillator","authors":"Munehisa Sekikawa ,&nbsp;Naohiko Inaba","doi":"10.1016/j.physleta.2025.130347","DOIUrl":"10.1016/j.physleta.2025.130347","url":null,"abstract":"<div><div>This Letter investigates the canards generated by a slow–fast hard-type van der Pol oscillator numerically. “Hard-type” oscillators are those that can simultaneously exhibit a stable equilibrium, a stable relaxation oscillation, and an unstable limit cycle; the possibility of this coexistence is due to the structure of the oscillator that contains a nonlinear element characterized by a fifth-order polynomial. In this Letter, we create a two-parameter bifurcation diagram in which both supercritical and subcritical Andronov–Hopf bifurcations and canard explosions are confirmed. We observe that the stable canard in this oscillator exhibits two explosion events. Furthermore, the oscillator exhibits an unstable canard, which also exhibits an explosion. These stable and unstable canards transform into large oscillations and disappear via a saddle-node bifurcation. We note that both the two sequential canard explosions as well as the unstable canard observed here represent novel phenomena that have not been observed prior to this work.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"538 ","pages":"Article 130347"},"PeriodicalIF":2.3,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Angular surface magnetostatic spin wave envelope soliton in a micrometer-sized tube","authors":"D.E. Saldanha-Bautista ,&nbsp;André C.A. Siqueira ,&nbsp;G. Palacios ,&nbsp;E. Padrón-Hernández","doi":"10.1016/j.physleta.2025.130344","DOIUrl":"10.1016/j.physleta.2025.130344","url":null,"abstract":"<div><div>Scientific exploration amalgamates nonlinear optics and magnetic phenomena, revealing a juncture where solitons emerge as distinct entities transcending multiple disciplines. In this study, we explore the nonlinear characteristics of non-exchange magnetostatic spin waves (MSW) generated within a micrometer-sized ferromagnetic hollow tube through four-magnon self-action processes. The study was based on the dynamical equations that capture the evolution of both, angular and longitudinal envelope solitons while expanding the dispersion relation near the resonance. The Analytical calculations are specifically focused on ferromagnetic structures employing Permalloy, <span><math><mi>N</mi><msub><mrow><mi>i</mi></mrow><mrow><mn>80</mn></mrow></msub><mi>F</mi><msub><mrow><mi>e</mi></mrow><mrow><mn>20</mn></mrow></msub></math></span>. This study is new in the literature, perhaps due to the geometry adopted, opening a wide spectrum of applications in spintronics.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"537 ","pages":"Article 130344"},"PeriodicalIF":2.3,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143395372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Computational screening of Ti-Based YTi3H8 (Y = Na, K and Rb) hydrides for efficient solid-state hydrogen storage system","authors":"Bilal Ahmed ,&nbsp;Muhammad Bilal Tahir ,&nbsp;Muhammad Sagir ,&nbsp;N. Dhahri","doi":"10.1016/j.physleta.2025.130345","DOIUrl":"10.1016/j.physleta.2025.130345","url":null,"abstract":"<div><div>There has been a lot of recent interest on hydrogen storage due to the fact that hydrogen may be utilized as an energy source. Evaluation of newly synthesized compounds' hydrogen storage capabilities has dominated studies on hydrogen storage applications. For the first time, density functional theory (DFT) calculations have been run to study the unique characteristics and hydrogen storage capabilities of the YTi₃H₈ (<em>Y</em> = Na, K, and Rb) compounds. The lattice constants for the compounds being studied are 4.85 Å for RbTi₃H₈, 4.74 Å for KTi₃H₈, and 4.54 Å for NaTi₃H₈ when optimized in the cubic phase. These hydrides have negative formation enthalpy, which means they are thermodynamically stable. High gravimetric hydrogen storage densities of 4.62 % for NaTi₃H₈, 4.23 % for KTi₃H₈, and 3.40 % for RbTi₃H₈ make YTi₃H₈ (<em>Y</em> = Na, K, and Rb) a promising candidate for hydrogen storage. In addition, the electronic properties of these compounds lend credence to their metallic properties. Furthermore, these compounds satisfy the Born stability conditions as shown by examination of the mechanical properties obtained from elastic constants, such as Pugh's ratio and Young's modulus. While both NaTi₃H₈ and KTi₃H₈ hydrides are brittle, Pugh's ratio and Cauchy pressure show that KTi₃H₈ hydride is ductile. The mechanical stability, high hydrogen storage capacity, and metallic nature of YTi₃H₈ (<em>Y</em> = Na, K, and Rb) indicate that they might be used in solid-state hydrogen storage devices. Fuel cell technologies, hydrogen-powered cars, and stationary energy storage applications can benefit from their stability and high hydrogen content, making them potential candidates for sustainable hydrogen energy solutions.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"538 ","pages":"Article 130345"},"PeriodicalIF":2.3,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Site preference of Cu and its influence on martensitic transformation and magnetic properties of Heusler alloy Mn2NiGa0.5Cu0.5","authors":"Haopeng Zhang ,&nbsp;Xin Li ,&nbsp;Hongxu Wang ,&nbsp;Sushuang Shi ,&nbsp;Jianqiang Li ,&nbsp;Hongzhi Luo","doi":"10.1016/j.physleta.2025.130346","DOIUrl":"10.1016/j.physleta.2025.130346","url":null,"abstract":"<div><div>Rietveld refinement of Heusler alloys Mn₂NiGa_1-xCu_x (<em>x</em> = 0.1, 0.3 and 0.5) XRD patterns confirms that doping element Cu occupies both A and D site simultaneously. And a higher percentage of Cu tends to occupy the D site with increasing Cu content. To investigate the influence of Cu occupation on martensitic transformation and magnetism, first-principles calculations on Mn₂NiGa_0.5Cu_0.5 with different Cu occupation between A, D sites were performed. In Mn₂NiGa_0.5Cu_0.5 austenite, with more Cu occupying D site, the phase stability increases and equilibrium lattice constant decreases. Cu entering the D site can enhance antiferromagnetic coupling between Mn (B) and Mn (A) spin moment, which leads to a rapid decrease of total moment of the austenite. The martensite-austenite energy difference ΔE_M shows an increasing tendency with more Cu occupying the D site, which helps to improve the martensitic transformation temperature and can be explained by the electronic structure calculations.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"537 ","pages":"Article 130346"},"PeriodicalIF":2.3,"publicationDate":"2025-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143402815","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Light localization near the interface between two crystals with sign-change nonlinearity and the index gradient","authors":"S.E. Savotchenko","doi":"10.1016/j.physleta.2025.130339","DOIUrl":"10.1016/j.physleta.2025.130339","url":null,"abstract":"<div><div>New nonlinear interface waves corresponding to two different cases of a change in the nonlinearity signs are described analytically. The waves propagate along the planar interface between nonlinear and spatially gradient crystals with a hyperbolic profile of the dielectric constant. The combination of the refractive index gradient and nonlinearity allows us to obtain new dispersion properties of the waveguide structure. New exact analytical solutions describing the light nonlinear wave intensity distribution in the transverse direction to the interface is found. The influence of the optical parameters on the patterns of the light localization is described. New effects are found when changing the signs of nonlinearity to the opposite ones. The power flow carried by the interface wave is analytically calculated and analyzed. It is shown that varying the optical parameters allows controlling the distribution of energy flow density between the layers of the crystalline system.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"538 ","pages":"Article 130339"},"PeriodicalIF":2.3,"publicationDate":"2025-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparing the optical and thermodynamic properties of 2D YLaX (X= C, N) MXenes to YLaB MBene: Ab-initio study","authors":"Maryam Heidary,&nbsp;Peiman Amiri","doi":"10.1016/j.physleta.2025.130340","DOIUrl":"10.1016/j.physleta.2025.130340","url":null,"abstract":"<div><div>Our investigation focuses on the optical and thermodynamic characteristics of YLaX (X = C, N, and B) compounds. The Quantum-ESPRESSO/PWSCF code, based on density functional theory and pseudopotential approach is used to carry out the calculations. The metallic and Drude-like behavior of the investigated compounds is indicated by significant negative values of ε₁(ω). The compounds YLaC, YLaN, and YLaB exhibit plasmon peaks in the x-direction within the GGA approximation for incoming photon energies of 13.34, 15.57, and 13.52 eV. Notably, YLaN has the greatest plasmon peak in both x and z-directions within GGA and HSE06 approximations. In the ultraviolet region of the electromagnetic spectrum, the incident light has its highest reflectance and absorption coefficient under the HSE approximation. This feature makes the studied monolayers suitable for use in optoelectronic devices. MXenes have a higher absorbance than YLaB MBene, according to the absorption spectrum. The GGA+HSE06 approximation lowers the absorption as compared to GGA and facilitates easier electromagnetic wave propagation in matter. The endothermic nature of YLaC, YLaN, and YLaB monolayers is attributed to the rising trend of entropy as the temperature increases. Because YLaN has a higher Debye temperature, it has the smallest lattice constant and the highest stiffness at infinitesimal temperatures.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"537 ","pages":"Article 130340"},"PeriodicalIF":2.3,"publicationDate":"2025-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143402814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Novel resonant soliton interactions for the Konopelchenko-Dubrovsky equation","authors":"Yu-Qiang Yuan ,&nbsp;Xiang Luo ,&nbsp;Yan Sun ,&nbsp;Lei Liu","doi":"10.1016/j.physleta.2025.130331","DOIUrl":"10.1016/j.physleta.2025.130331","url":null,"abstract":"<div><div>This paper investigates the resonant soliton interactions for the (<span><math><mn>2</mn><mo>+</mo><mn>1</mn></math></span>)-dimensional Konopelchenko-Dubrovsky equation, a model that describes shallow water waves with weak nonlinear restoring forces. Through symbolic computation and asymptotic analysis, we make a comprehensive classification of the resonant interactions between two solitons. Such equation admits both bell-shaped solitons and kink solitons, and allows us to identify four distinct types of resonance interactions, expanding beyond the common two cases. A novel discovery is the resonant interaction between a bell-shaped soliton and a kink soliton, where the bell-shaped soliton transforms into a kink soliton, which has not been reported before. Detailed graphical analyses are presented, providing clear visual representations of the soliton behaviors and their dynamic interactions. The results obtained in this study offer new insights into the complexity of soliton dynamics in higher-dimensional nonlinear systems.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"537 ","pages":"Article 130331"},"PeriodicalIF":2.3,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143379372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"One-dimensional photonic crystal-based optical diodes for pulse sources","authors":"Mahnaz Javid ,&nbsp;Samad Roshan Entezar ,&nbsp;Amir Madani","doi":"10.1016/j.physleta.2025.130330","DOIUrl":"10.1016/j.physleta.2025.130330","url":null,"abstract":"<div><div>This study explores the non-reciprocal characteristics of one-dimensional photonic crystals with Weyl semimetals, exposed to Gaussian laser pulses, utilizing the transfer matrix method. The non-reciprocity of the structure is examined by analyzing the impact of three variables on the contrast and the power ratio of transmitted to input: the pulse carrier frequency's relative position to the defect modes' peak frequency, the pulse duration, and the number of defect layers. The results indicate that by adjusting the carrier frequencies close to the defect mode frequency and minimizing the pulse width so that its power spectrum matches the defect mode frequency width, one can achieve both high contrast and a high transmitted-to-input power ratio. Moreover, increasing the number of defect layers extends the frequency range for high contrast but diminishes the power ratio. These insights are valuable for the design of non-reciprocal photonic devices.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"537 ","pages":"Article 130330"},"PeriodicalIF":2.3,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143379373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Intravalley Andreev reflection in the multi-terminal device with Y-shaped Kekulé graphene superlattices","authors":"Chao Wang ,&nbsp;Peipei Zhang ,&nbsp;Yu-Xian Li ,&nbsp;Juntao Song","doi":"10.1016/j.physleta.2024.130191","DOIUrl":"10.1016/j.physleta.2024.130191","url":null,"abstract":"<div><div>Using the tight-binding model, a multi-terminal superconductor (S) device is proposed, where the structures of the center region are primitive graphene (G) or Y-shaped Kekulé graphene superlattice (GS). The intravalley Andreev reflection is studied in this model through the utilization of the non-equilibrium Green's function method. In the G/S device, due to the time-reverse symmetry the dominant process of Andreev reflection is intervalley reflection. In the three-terminal GS/S device, it has been observed that with the time reversal symmetry the coefficient of intravalley Andreev reflection can surpass that of intervalley reflection in Andreev specular reflection. This is attributed to the coupling between valleys K and -K within the first Brillouin zone, resulting in enhanced intervalley scattering. The valley-dependent transport of Andreev reflection can be influenced by the phase difference between superconductor terminals. The valley polarization of the Andreev retro-reflection and the Andreev specular reflection could be controlled by adjusting the structure of the central region.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"532 ","pages":"Article 130191"},"PeriodicalIF":2.3,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143155627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An enhanced hybrid HHL algorithm","authors":"Jack Morgan ,&nbsp;Eric Ghysels ,&nbsp;Hamed Mohammadbagherpoor","doi":"10.1016/j.physleta.2024.130181","DOIUrl":"10.1016/j.physleta.2024.130181","url":null,"abstract":"<div><div>We present a classical enhancement to improve the accuracy of the Hybrid variant (Hybrid HHL) of the quantum algorithm for solving linear systems of equations proposed by Harrow, Hassidim, and Lloyd (HHL). We achieve this by using higher precision quantum estimates of the eigenvalues relevant to the linear system, and a new classical step to guide the eigenvalue inversion part of Hybrid HHL. We show that eigenvalue estimates with just two extra bits of precision result in tighter error bounds for our Enhanced Hybrid HHL compared to HHL. Our enhancement reduces the error of Hybrid HHL by an average of 57 percent on an ideal quantum processor for a representative sample of 2x2 systems. On IBM Torino and IonQ Aria-1 hardware, we see that the error of Enhanced Hybrid HHL is on average 13 percent and 20 percent (respectively) less than that of HHL for the same set of systems.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"532 ","pages":"Article 130181"},"PeriodicalIF":2.3,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143155637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}