Pub Date : 2024-07-01DOI: 10.1088/1674-1056/ad5d64
Tijjani Abdulrazak, Xuejuan Liu, Zhenyu Wang, Yunshan Cao, Peng Yan
In this study, we investigate the skyrmion motion driven by spin waves in magnetic nanotubes through micromagnetic simulations. Our key contributions include demonstrating the stability and enhanced mobility of skyrmions in the edgeless nanotube geometry, which prevents destruction at boundaries—a common issue in planar geometries. We explore the influence of the damping coefficient, amplitude, and frequency of microwaves on skyrmion dynamics, revealing a non-uniform velocity profile characterized by acceleration and deceleration phases. Our results show that the skyrmion Hall effect is significantly amplified in nanotubes compared to planar models, with specific dependencies on the spin-wave parameters. Notably, the skyrmion Hall angle remains consistent across varying damping coefficients and frequencies but changes when the driving field amplitude exceeds a threshold value. These findings provide insights into skyrmion manipulation for spintronic applications, highlighting the potential for high-speed and efficient information transport in magnonic devices.
{"title":"Skyrmion motion induced by spin-waves in magnetic nanotubes","authors":"Tijjani Abdulrazak, Xuejuan Liu, Zhenyu Wang, Yunshan Cao, Peng Yan","doi":"10.1088/1674-1056/ad5d64","DOIUrl":"https://doi.org/10.1088/1674-1056/ad5d64","url":null,"abstract":"\u0000 In this study, we investigate the skyrmion motion driven by spin waves in magnetic nanotubes through micromagnetic simulations. Our key contributions include demonstrating the stability and enhanced mobility of skyrmions in the edgeless nanotube geometry, which prevents destruction at boundaries—a common issue in planar geometries. We explore the influence of the damping coefficient, amplitude, and frequency of microwaves on skyrmion dynamics, revealing a non-uniform velocity profile characterized by acceleration and deceleration phases. Our results show that the skyrmion Hall effect is significantly amplified in nanotubes compared to planar models, with specific dependencies on the spin-wave parameters. Notably, the skyrmion Hall angle remains consistent across varying damping coefficients and frequencies but changes when the driving field amplitude exceeds a threshold value. These findings provide insights into skyrmion manipulation for spintronic applications, highlighting the potential for high-speed and efficient information transport in magnonic devices.","PeriodicalId":504421,"journal":{"name":"Chinese Physics B","volume":"96 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141695608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-15DOI: 10.1088/1674-1056/ad58b3
Jingyang Xu, Li Guo, Xin Qi, R. Lu, Min Zhang, Jingtao Zhang, Jing Chen
A Wigner-distribution-like (WDL) function based on the strong-field approximation (SFA) theory is used to investigate the ionization time of the photoelectron emitted from the initial states with different magnetic quantum number m in elliptically polarized electric fields. The saddle-point method is adopted for comparison. For different m states, a discrepancy exists in the WDL distributions of the photoelectrons emitted in a direction close to the major axis of the laser field ellipse. Based on the saddle-point analysis, this discrepancy can be ascribed to the interference between electrons ionized from two tunneling instants. Our results show that the relationships between the tunneling instants and kinetic energy of the photoelectrons are the same for different m initial states when the Coulomb potential is not considered. Our work sheds some light on the ionization-time information of electrons from different magnetic quantum states.
基于强场近似（SFA）理论的 Wigner 分布样（WDL）函数被用来研究椭圆极化电场中不同磁量子数 m 的初始态发射的光电子的电离时间。采用鞍点法进行比较。对于不同的 m 状态，在靠近激光场椭圆主轴方向发射的光电子的 WDL 分布存在差异。根据鞍点分析，这种差异可归因于两个隧道瞬时电离的电子之间的干扰。我们的研究结果表明，在不考虑库仑势的情况下，不同 m 初始状态下的隧道瞬时与光电子动能之间的关系是相同的。我们的研究揭示了不同磁量子态电子的电离时间信息。
{"title":"Time-energy distribution of photoelectron from atomic states with different magnetic quantum numbers in elliptically polarized laser fields","authors":"Jingyang Xu, Li Guo, Xin Qi, R. Lu, Min Zhang, Jingtao Zhang, Jing Chen","doi":"10.1088/1674-1056/ad58b3","DOIUrl":"https://doi.org/10.1088/1674-1056/ad58b3","url":null,"abstract":"\u0000 A Wigner-distribution-like (WDL) function based on the strong-field approximation (SFA) theory is used to investigate the ionization time of the photoelectron emitted from the initial states with different magnetic quantum number m in elliptically polarized electric fields. The saddle-point method is adopted for comparison. For different m states, a discrepancy exists in the WDL distributions of the photoelectrons emitted in a direction close to the major axis of the laser field ellipse. Based on the saddle-point analysis, this discrepancy can be ascribed to the interference between electrons ionized from two tunneling instants. Our results show that the relationships between the tunneling instants and kinetic energy of the photoelectrons are the same for different m initial states when the Coulomb potential is not considered. Our work sheds some light on the ionization-time information of electrons from different magnetic quantum states.","PeriodicalId":504421,"journal":{"name":"Chinese Physics B","volume":"78 14","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141337778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-15DOI: 10.1088/1674-1056/ad58b2
Hui Zhou, Xiaoli Dai, Jianpei Geng, Yunlan Ji, Xinhua Peng
Counterdiabatic driving (CD) offers a fast and robust route to manipulate quantum systems, which has widespread applications in quantum technologies. However, for higher-dimensional complex systems, the exact CD term involving the spectral properties of the system is difficult to calculate and generally takes a complicated form, impeding its experimental realization. Recently, many approximate methods have been proposed for designing CD passages in many-body systems. In this topical review, we focus on the CD formalism and briefly introduce several experimental constructions and applications of approximate CD driving in spin-chain models with nuclear magnetic resonance (NMR) systems.
逆绝热驱动（CD）为操纵量子系统提供了一条快速而稳健的途径，在量子技术领域有着广泛的应用。然而，对于高维复杂系统，涉及系统频谱特性的精确逆绝热项难以计算，且通常形式复杂，阻碍了其实验实现。最近，人们提出了许多近似方法来设计多体系统中的 CD 通道。在这篇专题综述中，我们将重点讨论 CD 形式主义，并简要介绍核磁共振（NMR）系统自旋链模型中近似 CD 驱动的几种实验构造和应用。
{"title":"Approximate constructions of counterdiabatic driving with NMR quantum systems","authors":"Hui Zhou, Xiaoli Dai, Jianpei Geng, Yunlan Ji, Xinhua Peng","doi":"10.1088/1674-1056/ad58b2","DOIUrl":"https://doi.org/10.1088/1674-1056/ad58b2","url":null,"abstract":"\u0000 Counterdiabatic driving (CD) offers a fast and robust route to manipulate quantum systems, which has widespread applications in quantum technologies. However, for higher-dimensional complex systems, the exact CD term involving the spectral properties of the system is difficult to calculate and generally takes a complicated form, impeding its experimental realization. Recently, many approximate methods have been proposed for designing CD passages in many-body systems. In this topical review, we focus on the CD formalism and briefly introduce several experimental constructions and applications of approximate CD driving in spin-chain models with nuclear magnetic resonance (NMR) systems.","PeriodicalId":504421,"journal":{"name":"Chinese Physics B","volume":"13 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141337232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The orbital angular momentum (OAM) conversion is critical in understanding the interaction between the structural sound field and a planar lattice. Herein, we explored the evolution of a monochromatic acoustic vortex beam (AVB) that is scattered by a phononic crystal (PnC) or a correlated random lattice. The phenomenon is ascribed to the enhanced orbit-orbit angular momentum coupling induced by the band structure. By modifying the coupling condition, accurate and continuous micro-manipulation of the AVBs can be achieved, including the transverse/lateral gravity shift, the dynamics of the phase singularities, the spatial distribution of acoustic pressure and etc. This research provides insight to the inhomogeneous coupling of AVBs with both the propagating Bloch waves and the localized Anderson modes, and may facilitate the development of novel OAM-based acoustic devices for active sound field manipulation.
{"title":"Orbital Angular Momentum Conversion of Acoustic Vortex Beams via Planar Lattice Coupling","authors":"Qingbang Han, Zhipeng Liu, Cheng Yi, Simeng Wu, Yinlong Luo, Zixin Yang, Xiuyang Pang, Yiqiu Wang, X. Kan, Yuqiu Zhang, Qiang Yu, Jian Wu","doi":"10.1088/1674-1056/ad57ad","DOIUrl":"https://doi.org/10.1088/1674-1056/ad57ad","url":null,"abstract":"\u0000 The orbital angular momentum (OAM) conversion is critical in understanding the interaction between the structural sound field and a planar lattice. Herein, we explored the evolution of a monochromatic acoustic vortex beam (AVB) that is scattered by a phononic crystal (PnC) or a correlated random lattice. The phenomenon is ascribed to the enhanced orbit-orbit angular momentum coupling induced by the band structure. By modifying the coupling condition, accurate and continuous micro-manipulation of the AVBs can be achieved, including the transverse/lateral gravity shift, the dynamics of the phase singularities, the spatial distribution of acoustic pressure and etc. This research provides insight to the inhomogeneous coupling of AVBs with both the propagating Bloch waves and the localized Anderson modes, and may facilitate the development of novel OAM-based acoustic devices for active sound field manipulation.","PeriodicalId":504421,"journal":{"name":"Chinese Physics B","volume":"16 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141348474","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-13DOI: 10.1088/1674-1056/ad57ac
Qingjie Zhang, Hui Xing, Lingjie Wang, Wei Zhai
In this paper, the effect of undercooling △T and the interface energy anisotropy parameter ε 4 on the shape of the equiaxed dendritic tip has been investigated by using a quantitative phase-field model for solidification of binary alloys. It was found that the tip radius ρ increases and the tip shape amplitude coefficient A 4 decreases with the increase of the fitting range for all cases. The dendrite tip shape selection parameter σ * decreases and then stabilizes with the increase of the fitting range, and σ * increases with the increase of ε 4. The relationship between σ * and ε 4 follows a power law function σ * ∝ ε 4 α, and is independent of but dependent of the fitting range. Numerical results demonstrate that the predicted σ * is consistent with the MST curve for ε 4 ＜ 0.02, and σ * obtained from our phase-field simulations is sensitive to the undercooling when ε 4 is fixed.
{"title":"Dendritic tip selection during solidification of alloys: Insights from phase-field simulations","authors":"Qingjie Zhang, Hui Xing, Lingjie Wang, Wei Zhai","doi":"10.1088/1674-1056/ad57ac","DOIUrl":"https://doi.org/10.1088/1674-1056/ad57ac","url":null,"abstract":"\u0000 In this paper, the effect of undercooling △T and the interface energy anisotropy parameter ε\u0000 4 on the shape of the equiaxed dendritic tip has been investigated by using a quantitative phase-field model for solidification of binary alloys. It was found that the tip radius ρ increases and the tip shape amplitude coefficient A\u0000 4 decreases with the increase of the fitting range for all cases. The dendrite tip shape selection parameter σ\u0000 * decreases and then stabilizes with the increase of the fitting range, and σ\u0000 * increases with the increase of ε\u0000 4. The relationship between σ\u0000 * and ε\u0000 4 follows a power law function σ\u0000 * ∝ ε\u0000 4\u0000 α, and is independent of but dependent of the fitting range. Numerical results demonstrate that the predicted σ\u0000 * is consistent with the MST curve for ε\u0000 4 ＜ 0.02, and σ\u0000 * obtained from our phase-field simulations is sensitive to the undercooling when ε\u0000 4 is fixed.","PeriodicalId":504421,"journal":{"name":"Chinese Physics B","volume":"51 15","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141349411","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The heat transfer and stability of methane hydrate in reservoirs have a direct impact on the drilling and production efficiency of hydrate resources, especially in complex stress environments caused by formation subsidence. Herein, we investigated the thermal transport and structural stability of methane hydrate under triaxial compressions using molecular dynamics (MD) simulations. The results suggest that the thermal conductivity of methane hydrate increases with increasing compression strains. Two phonon transport mechanisms were identified as factors enhancing thermal conductivity: At low compressive strains, a low-frequency phonon transport channel was established due to the overlap of phonon vibration peaks between methane and water molecules. At high compressive strains, the filling of larger phonon band gaps facilitated the opening of more phonon transport channels. Additionally, we found that a strain of -0.04 is a watershed point where methane hydrate transitions from stable to unstable. Furthermore, a strain of -0.06 marks the threshold at which the diffusion capacity of methane and water molecules is at its peak. At a higher strain of -0.08, the increased volume compression reduces the available space, limiting the diffusion ability of water and methane molecules within the hydrate. The synergistic effect of strong diffusion ability and high probability of collision between atoms increases the thermal conductivity of hydrates during the unstable period compared to the stable period. Our findings offer valuable theoretical insights into the thermal conductivity and stability of methane hydrates under reservoir stress environments.
{"title":"Theoretical insight into thermal transport and structural stability mechanisms of triaxial compressed methane hydrate","authors":"Dong-Sheng Chen, Ting-Ting Miao, Cheng Chang, Xuyang Guo, Meng-Yan Guan, Zhongli Ji","doi":"10.1088/1674-1056/ad57ae","DOIUrl":"https://doi.org/10.1088/1674-1056/ad57ae","url":null,"abstract":"\u0000 The heat transfer and stability of methane hydrate in reservoirs have a direct impact on the drilling and production efficiency of hydrate resources, especially in complex stress environments caused by formation subsidence. Herein, we investigated the thermal transport and structural stability of methane hydrate under triaxial compressions using molecular dynamics (MD) simulations. The results suggest that the thermal conductivity of methane hydrate increases with increasing compression strains. Two phonon transport mechanisms were identified as factors enhancing thermal conductivity: At low compressive strains, a low-frequency phonon transport channel was established due to the overlap of phonon vibration peaks between methane and water molecules. At high compressive strains, the filling of larger phonon band gaps facilitated the opening of more phonon transport channels. Additionally, we found that a strain of -0.04 is a watershed point where methane hydrate transitions from stable to unstable. Furthermore, a strain of -0.06 marks the threshold at which the diffusion capacity of methane and water molecules is at its peak. At a higher strain of -0.08, the increased volume compression reduces the available space, limiting the diffusion ability of water and methane molecules within the hydrate. The synergistic effect of strong diffusion ability and high probability of collision between atoms increases the thermal conductivity of hydrates during the unstable period compared to the stable period. Our findings offer valuable theoretical insights into the thermal conductivity and stability of methane hydrates under reservoir stress environments.","PeriodicalId":504421,"journal":{"name":"Chinese Physics B","volume":"31 26","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141345966","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-13DOI: 10.1088/1674-1056/ad57aa
Xiao-wei Jin, Tong Li, Hui-gang Shi, De-sheng Xue
Nowadays, lack of soft magnetic composites with high power density in MHz frequency range has become an obstacle in efficient operation of the electrical and electronic equipment. Here, a promising method to increase the cut-off frequency of iron-based soft magnetic composites to hundreds MHz is reported. The cut-off frequency is increased from 10 MHz to 1 GHz by modulating the height of ring, the distribution of particles, and the particle size. The mechanism of cut-off frequency and permeability is the coherent rotation of domain modulated by inhomogeneous field due to the eddy current effect. An empirical formula for cut-off frequency in magnetic ring composed of iron-based particles is established from experimental data. This work provides an effective approach to fabricate soft magnetic composites with a cut-off frequency in the hundreds of MHz.
{"title":"MHz cut-off frequency and permeability mechanism of iron-based soft magnetic composites","authors":"Xiao-wei Jin, Tong Li, Hui-gang Shi, De-sheng Xue","doi":"10.1088/1674-1056/ad57aa","DOIUrl":"https://doi.org/10.1088/1674-1056/ad57aa","url":null,"abstract":"\u0000 Nowadays, lack of soft magnetic composites with high power density in MHz frequency range has become an obstacle in efficient operation of the electrical and electronic equipment. Here, a promising method to increase the cut-off frequency of iron-based soft magnetic composites to hundreds MHz is reported. The cut-off frequency is increased from 10 MHz to 1 GHz by modulating the height of ring, the distribution of particles, and the particle size. The mechanism of cut-off frequency and permeability is the coherent rotation of domain modulated by inhomogeneous field due to the eddy current effect. An empirical formula for cut-off frequency in magnetic ring composed of iron-based particles is established from experimental data. This work provides an effective approach to fabricate soft magnetic composites with a cut-off frequency in the hundreds of MHz.","PeriodicalId":504421,"journal":{"name":"Chinese Physics B","volume":"44 19","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141345180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-13DOI: 10.1088/1674-1056/ad57ab
Ze-Hao Chen, Zhi-Xi Wu, Jian-Yue Guan
We adopt a floor field cellular automata model to study the statistical properties of bidirectional pedestrian flow moving in a straight corridor. We introduce a game-theoretic framework to deal with the conflict of multiple pedestrians trying to move to the same target location. By means of computer simulations, we show that the complementary cumulative distribution of the time interval between two consecutive pedestrians leaving the corridor can be fitted by a stretched exponential distribution, and surprisingly, the statistical properties of the two types of pedestrian flows are affected differently by the flow ratio, i.e., the ratio of the pedestrians walking toward different directions. We also find that the jam probability exhibits a nonmonotonic behavior with the flow ratio, where the worst performance arises at an intermediate flow ratio of around 0.2. Our simulation results are consistent with some empirical observations, which suggest that the peculiar characteristics of the pedestrians may attributed to the anticipation mechanism of collision avoidance.
{"title":"Non-monotonic behavior of jam probability and stretched exponential distribution in pedestrian counterflow","authors":"Ze-Hao Chen, Zhi-Xi Wu, Jian-Yue Guan","doi":"10.1088/1674-1056/ad57ab","DOIUrl":"https://doi.org/10.1088/1674-1056/ad57ab","url":null,"abstract":"\u0000 We adopt a floor field cellular automata model to study the statistical properties of bidirectional pedestrian flow moving in a straight corridor. We introduce a game-theoretic framework to deal with the conflict of multiple pedestrians trying to move to the same target location. By means of computer simulations, we show that the complementary cumulative distribution of the time interval between two consecutive pedestrians leaving the corridor can be fitted by a stretched exponential distribution, and surprisingly, the statistical properties of the two types of pedestrian flows are affected differently by the flow ratio, i.e., the ratio of the pedestrians walking toward different directions. We also find that the jam probability exhibits a nonmonotonic behavior with the flow ratio, where the worst performance arises at an intermediate flow ratio of around 0.2. Our simulation results are consistent with some empirical observations, which suggest that the peculiar characteristics of the pedestrians may attributed to the anticipation mechanism of collision avoidance.","PeriodicalId":504421,"journal":{"name":"Chinese Physics B","volume":"38 13","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141349805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-07DOI: 10.1088/1674-1056/ad5534
Qi Li, Junfeng Liu, Ke Liu, Zi-Xiang Hu, Zhou Li
We develop a numerical method for the time evolution of Gaussian wave packets on flat-band lattices in the presence of correlated disorder. To achieve this, we introduce a method to generate random on-site energies with prescribed correlations. We verify this method with a one-dimensional (1D) cross-stitch model, and find good agreement with analytical results obtained from the disorderdressed evolution equations. This allows us to reproduce previous findings, that disorder can mobilize 1D flat-band states which would otherwise remain localized. As explained by the corresponding disorder-dressed evolution equations, such mobilization requires an asymmetric disorder-induced coupling to dispersive bands, a condition that is generically not fulfilled when the flat-band is resonant with the dispersive bands at a Dirac point-like crossing. We exemplify this with the 1D Lieb lattice. While analytical expressions are not available for the two-dimensional (2D) system due to its complexity, we extend the numerical method to the 2D α-T 3 model, and find that the initial flat-band wave packet preserves its localization when α = 0, regardless of disorder and intersections. However, when α ≠ 0, the wave packet shifts in real space. We interpret this as a Berry phase controlled, disorder-induced wave-packet mobilization. In addition, we present density functional theory calculations of candidate materials, specifically Hg1-xCdxTe. The flat-band emerges near the Γ point (k =0) in the Brillouin zone.
{"title":"Non-perturbative dynamics of flat-band systems with correlated disorder","authors":"Qi Li, Junfeng Liu, Ke Liu, Zi-Xiang Hu, Zhou Li","doi":"10.1088/1674-1056/ad5534","DOIUrl":"https://doi.org/10.1088/1674-1056/ad5534","url":null,"abstract":"\u0000 We develop a numerical method for the time evolution of Gaussian wave packets on flat-band lattices in the presence of correlated disorder. To achieve this, we introduce a method to generate random on-site energies with prescribed correlations. We verify this method with a one-dimensional (1D) cross-stitch model, and find good agreement with analytical results obtained from the disorderdressed evolution equations. This allows us to reproduce previous findings, that disorder can mobilize 1D flat-band states which would otherwise remain localized. As explained by the corresponding disorder-dressed evolution equations, such mobilization requires an asymmetric disorder-induced coupling to dispersive bands, a condition that is generically not fulfilled when the flat-band is resonant with the dispersive bands at a Dirac point-like crossing. We exemplify this with the 1D Lieb lattice. While analytical expressions are not available for the two-dimensional (2D) system due to its complexity, we extend the numerical method to the 2D α-T\u0000 3 model, and find that the initial flat-band wave packet preserves its localization when α = 0, regardless of disorder and intersections. However, when α ≠ 0, the wave packet shifts in real space. We interpret this as a Berry phase controlled, disorder-induced wave-packet mobilization. In addition, we present density functional theory calculations of candidate materials, specifically Hg1-xCdxTe. The flat-band emerges near the Γ point (k =0) in the Brillouin zone.","PeriodicalId":504421,"journal":{"name":"Chinese Physics B","volume":" 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141373723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-07DOI: 10.1088/1674-1056/ad553c
Genhao Liang, Hui Cao, Long Cheng, Junkun Zha, Mingrui Bao, Fei Ye, Hua Zhou, Aidi Zhao, Xiaofang Zhai
Coexistence of ferromagnetism and ferroelasticity in a single material is an intriguing phenomenon, but has been rarely found. Here we study both the ferromagnetism and ferroelasticity in a group of LaCoO3 films with systematically tuned atomic structures. We found that all films exhibit ferroelastic domains with four-fold symmetry and the larger domain size (higher elasticity) is always accompanied with stronger ferromagnetism. We performed synchrotron X-ray diffraction studies to investigate the backbone structure of the CoO6 octahedra, and found that both the ferromagnetism and the elasticity are simultaneously enhanced when the in-plane Co-O-Co bond angles are straightened. Therefore the study demonstrates the inextricable correlation between the ferromagnetism and ferroelasticity mediated through the octahedral backbone structure, which may open up new possibilities to develop multifunctional materials.
在单一材料中同时存在铁磁性和铁弹性是一个有趣的现象，但却很少被发现。在这里，我们研究了一组原子结构经过系统调整的钴酸锂薄膜的铁磁性和铁弹性。我们发现，所有薄膜都表现出具有四重对称性的铁弹性域，而且域尺寸越大（弹性越高），铁磁性就越强。我们对 CoO6 八面体的骨架结构进行了同步辐射 X 射线衍射研究，发现当面内 Co-O-Co 键角变直时，铁磁性和弹性同时增强。因此，该研究证明了通过八面体骨架结构介导的铁磁性和铁弹性之间密不可分的关系，这为开发多功能材料提供了新的可能性。
{"title":"Simultaneous control of ferromagnetism and ferroelasticity by oxygen octahedral backbone stretching","authors":"Genhao Liang, Hui Cao, Long Cheng, Junkun Zha, Mingrui Bao, Fei Ye, Hua Zhou, Aidi Zhao, Xiaofang Zhai","doi":"10.1088/1674-1056/ad553c","DOIUrl":"https://doi.org/10.1088/1674-1056/ad553c","url":null,"abstract":"\u0000 Coexistence of ferromagnetism and ferroelasticity in a single material is an intriguing phenomenon, but has been rarely found. Here we study both the ferromagnetism and ferroelasticity in a group of LaCoO3 films with systematically tuned atomic structures. We found that all films exhibit ferroelastic domains with four-fold symmetry and the larger domain size (higher elasticity) is always accompanied with stronger ferromagnetism. We performed synchrotron X-ray diffraction studies to investigate the backbone structure of the CoO6 octahedra, and found that both the ferromagnetism and the elasticity are simultaneously enhanced when the in-plane Co-O-Co bond angles are straightened. Therefore the study demonstrates the inextricable correlation between the ferromagnetism and ferroelasticity mediated through the octahedral backbone structure, which may open up new possibilities to develop multifunctional materials.","PeriodicalId":504421,"journal":{"name":"Chinese Physics B","volume":" 40","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141375111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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