Localized states in graphene have garnered significant attention in quantum information science due to their potential applications. Despite graphene's superior transport and electronic properties compared to other semiconductors, achieving nanoscale confinement remains challenging due to its gapless nature. In this study, we explore the unique transport properties along nanowrinkles in monolayer graphene. We demonstrate the creation of a one-dimensional conduction channel by alternating pseudo-magnetic fields along the nanowrinkle, enabling ballistic Dirac fermion transport without leakage. This suggests a feasible method for secure quantum information transfer over long distances. Furthermore, we extend our analysis to bent nanowrinkles, showcasing well-guided Dirac fermion propagation unless the bent angle is sufficiently large. Our demonstration of the nanowrinkle waveguide in graphene introduces a novel approach to controlling Dirac fermion transport through strain engineering, for quantum information technology applications.
{"title":"Nanowrinkle Waveguide in Graphene for Enabling Secure Dirac Fermion Transport","authors":"Seunghyun Jun, Myung-Chul Jung, Nojoon Myoung","doi":"arxiv-2407.20148","DOIUrl":"https://doi.org/arxiv-2407.20148","url":null,"abstract":"Localized states in graphene have garnered significant attention in quantum\u0000information science due to their potential applications. Despite graphene's\u0000superior transport and electronic properties compared to other semiconductors,\u0000achieving nanoscale confinement remains challenging due to its gapless nature.\u0000In this study, we explore the unique transport properties along nanowrinkles in\u0000monolayer graphene. We demonstrate the creation of a one-dimensional conduction\u0000channel by alternating pseudo-magnetic fields along the nanowrinkle, enabling\u0000ballistic Dirac fermion transport without leakage. This suggests a feasible\u0000method for secure quantum information transfer over long distances.\u0000Furthermore, we extend our analysis to bent nanowrinkles, showcasing\u0000well-guided Dirac fermion propagation unless the bent angle is sufficiently\u0000large. Our demonstration of the nanowrinkle waveguide in graphene introduces a\u0000novel approach to controlling Dirac fermion transport through strain\u0000engineering, for quantum information technology applications.","PeriodicalId":501211,"journal":{"name":"arXiv - PHYS - Other Condensed Matter","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141872803","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}
S. Mukherjee, O. Ivashko, S. Majumdar, A. Kumar, S. Giri
Sm$_2$Ti$_2$O$_7$, a member of rare-earth titanate pyrochlores, exhibits dipolar-octupolar antiferromagnetism below $T_N$ = 0.35 K. We observed two ferroelectric transitions at 182 ($T_{FE1}$) and 52 K ($T_{FE2}$), significantly higher than $T_N$ for Sm$_2$Ti$_{2-x}$V$_x$O$_7$ ($x$ = 0, 0.1). Although the ferroelectric transition temperatures remain unchanged, the polarization value decreases considerably with V doping. A structural transition to a polar $R3m$ rhombohedral phase from the cubic $Fdbar{3}m$ structure occurs at $T_{FE1}$, involving a distortion in the pyochlore lattice. Remarkably, significant linear magnetoelectric coupling is observed in both compounds, with further enhancement of magnetoelectric coupling due to magnetic V doping. The existence of magnetoelectric coupling without long-range magnetic order in a frustrated pyrochlore system could enable the tailoring of magnetoelectric coupling properties, which can be further fine-tuned through V doping. The emergence of ferroelectricity in a frustrated magnetic system introduces an intriguing aspect to these compounds and paves the way for developing ferroelectric order driven by the alleviation of magnetic frustration in pyrochlore systems.
Sm$_2$Ti$_2$O$_7$ 是稀土钛酸盐火成岩的一种，在 $T_N$ = 0.35 K 以下表现出两极-八极反铁磁性。我们观察到 Sm$_2$Ti$_{2-x}$V$_x$O$_7$ ($x$=0，0.1) 在 182 ($T_{FE1}$) 和 52 K ($T_{FE2}$) 发生了两个铁电转换，明显高于 $T_N$。在 $T_{FE1}$ 时，结构从立方的 $Fdbar{3}m$ 结构转变为极性的 $R3m$ 菱形相，这涉及到菱形晶格的畸变。值得注意的是，在这两种化合物中都观察到了显著的线性磁电耦合，而磁性 V 掺杂又进一步增强了磁电耦合。掺杂磁性 V 可进一步增强磁电耦合。在受挫火绿宝石体系中存在无长程磁序的磁电耦合，这使得磁电耦合特性的定制成为可能，并可通过掺杂 V 对其进行进一步微调。在沮喪磁性體系中出現的鐵電性為這些化合物帶來了有趣的一面，並為在火成體系中緩解磁沮喪驅動鐵電秩序的發展鋪平了道路。
{"title":"Successive ferroelectric orders and magnetoelectric coupling without long-range magnetic order in highly frustrated pyrochlore compounds: Sm$_2$Ti$_{2-x}$V$_x$O$_7$","authors":"S. Mukherjee, O. Ivashko, S. Majumdar, A. Kumar, S. Giri","doi":"arxiv-2407.19883","DOIUrl":"https://doi.org/arxiv-2407.19883","url":null,"abstract":"Sm$_2$Ti$_2$O$_7$, a member of rare-earth titanate pyrochlores, exhibits\u0000dipolar-octupolar antiferromagnetism below $T_N$ = 0.35 K. We observed two\u0000ferroelectric transitions at 182 ($T_{FE1}$) and 52 K ($T_{FE2}$),\u0000significantly higher than $T_N$ for Sm$_2$Ti$_{2-x}$V$_x$O$_7$ ($x$ = 0, 0.1).\u0000Although the ferroelectric transition temperatures remain unchanged, the\u0000polarization value decreases considerably with V doping. A structural\u0000transition to a polar $R3m$ rhombohedral phase from the cubic $Fdbar{3}m$\u0000structure occurs at $T_{FE1}$, involving a distortion in the pyochlore lattice.\u0000Remarkably, significant linear magnetoelectric coupling is observed in both\u0000compounds, with further enhancement of magnetoelectric coupling due to magnetic\u0000V doping. The existence of magnetoelectric coupling without long-range magnetic\u0000order in a frustrated pyrochlore system could enable the tailoring of\u0000magnetoelectric coupling properties, which can be further fine-tuned through V\u0000doping. The emergence of ferroelectricity in a frustrated magnetic system\u0000introduces an intriguing aspect to these compounds and paves the way for\u0000developing ferroelectric order driven by the alleviation of magnetic\u0000frustration in pyrochlore systems.","PeriodicalId":501211,"journal":{"name":"arXiv - PHYS - Other Condensed Matter","volume":"74 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141872804","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}
Jacopo Nicoletti, Leonardo Puppulin, Julie Routurier, Saimir Frroku, Nouha Loudhaief, Claudia Crestini, Alvise Perosa, Maurizio Selva, Matteo Gigli, Domenico De Fazio, Giovanni Antonio Salvatore
Piezoelectricity, the generation of electric charge in response to mechanical stress, is a key property in both natural and synthetic materials. This study significantly boosts the piezoelectric response of chitosan, a biodegradable biopolymer, by integrating chitin/chitosan nanocrystals into natural chitosan-based thin film elastomers. The resulting materials achieve d$_{33}$ values of 15-19 pmV$^{-1}$, a marked improvement over the 5-9 pmV$^{-1}$ observed in pure chitosan films thanks to increased crystallinity from the nanocrystals. We utilize piezoresponse force microscopy (PFM) to accurately measure the d$_{33}$ coefficient, employing an engineered extraction method that eliminates the electrostatic contribution, which can overestimate the piezoelectric response. The resulting chitosan elastomers exhibit elastic deformation up to 40% strain and a Young's modulus of approximately 100 MPa, similar to soft tissues. These properties, along with the fact that the employed materials can be entirely crafted from upcycled biowaste, make these elastomers ideal for prosthetics, wearable devices, energy harvesters, and sustainable transducers. Our findings underscore the potential of chitosan-based piezoelectric materials for advanced applications in biotechnology, soft robotics, and the green Internet of Things.
{"title":"Enhanced Piezoelectricity in Sustainable-by-design Chitosan Nanocomposite Elastomers for Prosthetics, Robotics, and Circular Electronics","authors":"Jacopo Nicoletti, Leonardo Puppulin, Julie Routurier, Saimir Frroku, Nouha Loudhaief, Claudia Crestini, Alvise Perosa, Maurizio Selva, Matteo Gigli, Domenico De Fazio, Giovanni Antonio Salvatore","doi":"arxiv-2407.18585","DOIUrl":"https://doi.org/arxiv-2407.18585","url":null,"abstract":"Piezoelectricity, the generation of electric charge in response to mechanical\u0000stress, is a key property in both natural and synthetic materials. This study\u0000significantly boosts the piezoelectric response of chitosan, a biodegradable\u0000biopolymer, by integrating chitin/chitosan nanocrystals into natural\u0000chitosan-based thin film elastomers. The resulting materials achieve d$_{33}$\u0000values of 15-19 pmV$^{-1}$, a marked improvement over the 5-9 pmV$^{-1}$\u0000observed in pure chitosan films thanks to increased crystallinity from the\u0000nanocrystals. We utilize piezoresponse force microscopy (PFM) to accurately\u0000measure the d$_{33}$ coefficient, employing an engineered extraction method\u0000that eliminates the electrostatic contribution, which can overestimate the\u0000piezoelectric response. The resulting chitosan elastomers exhibit elastic\u0000deformation up to 40% strain and a Young's modulus of approximately 100 MPa,\u0000similar to soft tissues. These properties, along with the fact that the\u0000employed materials can be entirely crafted from upcycled biowaste, make these\u0000elastomers ideal for prosthetics, wearable devices, energy harvesters, and\u0000sustainable transducers. Our findings underscore the potential of\u0000chitosan-based piezoelectric materials for advanced applications in\u0000biotechnology, soft robotics, and the green Internet of Things.","PeriodicalId":501211,"journal":{"name":"arXiv - PHYS - Other Condensed Matter","volume":"363 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141873430","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}
Gavin Nop, Micah Mundy, Durga Paudyal, Jonathan Smith
Machine Learning (ML) is accelerating the progress of materials prediction and classification, with particular success in CGNN designs. While classical ML methods remain accessible, advanced deep networks are still challenging to build and train. We introduce two new adaptations and refine two existing ML networks for generic crystalline quantum materials properties prediction and optimization. These new models achieve state-of-the-art performance in predicting TQC classification and strong performance in predicting band gaps, magnetic classifications, formation energies, and symmetry group. All networks easily generalize to all quantum crystalline materials property predictions. To support this, full implementations and automated methods for data handling and materials predictions are provided, facilitating the use of deep ML methods in quantum materials science. Finally, dataset error rates are analyzed using an ensemble model to identify and highlight highly atypical materials for further investigations.
机器学习（ML）正在加速材料预测和分类的发展，其中 CGNN 设计尤为成功。虽然经典的 ML 方法仍然可以使用，但高级深度网络的构建和训练仍然具有挑战性。我们为通用晶体量子材料性能预测和优化引入了两个新的适应性模型，并改进了两个现有的 ML 网络。这些新模型在预测 TQC 分类方面达到了最先进的性能，在预测带隙、磁性分类、形成能和对称组方面表现出色。所有网络都能轻松地通用于所有量子晶体材料的属性预测。为了支持这一点，我们提供了数据处理和材料预测的完整实现和自动化方法，从而促进了深度 ML 方法在量子材料科学中的应用。最后，使用集合模型分析了数据集错误率，以识别并突出高度非典型材料，供进一步研究。
{"title":"Predicting quantum materials properties using novel faithful machine learning embeddings","authors":"Gavin Nop, Micah Mundy, Durga Paudyal, Jonathan Smith","doi":"arxiv-2407.18388","DOIUrl":"https://doi.org/arxiv-2407.18388","url":null,"abstract":"Machine Learning (ML) is accelerating the progress of materials prediction\u0000and classification, with particular success in CGNN designs. While classical ML\u0000methods remain accessible, advanced deep networks are still challenging to\u0000build and train. We introduce two new adaptations and refine two existing ML\u0000networks for generic crystalline quantum materials properties prediction and\u0000optimization. These new models achieve state-of-the-art performance in\u0000predicting TQC classification and strong performance in predicting band gaps,\u0000magnetic classifications, formation energies, and symmetry group. All networks\u0000easily generalize to all quantum crystalline materials property predictions. To\u0000support this, full implementations and automated methods for data handling and\u0000materials predictions are provided, facilitating the use of deep ML methods in\u0000quantum materials science. Finally, dataset error rates are analyzed using an\u0000ensemble model to identify and highlight highly atypical materials for further\u0000investigations.","PeriodicalId":501211,"journal":{"name":"arXiv - PHYS - Other Condensed Matter","volume":"44 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141862861","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}
Based on geometric phases of Bloch electrons computed from first-principles, we propose a scheme for unambiguous partitioning of charge in matter, derivable directly from the Kohn-Sham states. Generalizing the fact that geometric phases acquired by electrons due to evolution of their crystal momentum $vec k$ in a direction through out the Brillouin zone(BZ), provide position of their localization with net minimum spread along the corresponding direction in real space. We find that the total charge can be meaningfully distributed into charge centres simultaneously contributed by triads of electrons with their crystal momentum evolving linearly independently through each unique $vec k$ across the BZ. The resultant map of charge centres readily renders not only the qualitative nature of inter-atomic as well as intra-atomic hybridization of electrons, but also unbiased quantitative estimates of electrons on atoms or shared between them, as demonstrated in a select variety of isolated and periodic systems with varying degree of sharing of valence electrons among atoms, including variants of multi-centered bonds.
{"title":"Partitioning of total charge in matter from geometric phases of electrons","authors":"Joyeta Saha, Sujith Nedungattil Subrahmanian, Joydeep Bhattacharjee","doi":"arxiv-2407.17202","DOIUrl":"https://doi.org/arxiv-2407.17202","url":null,"abstract":"Based on geometric phases of Bloch electrons computed from first-principles,\u0000we propose a scheme for unambiguous partitioning of charge in matter, derivable\u0000directly from the Kohn-Sham states. Generalizing the fact that geometric phases\u0000acquired by electrons due to evolution of their crystal momentum $vec k$ in a\u0000direction through out the Brillouin zone(BZ), provide position of their\u0000localization with net minimum spread along the corresponding direction in real\u0000space. We find that the total charge can be meaningfully distributed into\u0000charge centres simultaneously contributed by triads of electrons with their\u0000crystal momentum evolving linearly independently through each unique $vec k$\u0000across the BZ. The resultant map of charge centres readily renders not only the\u0000qualitative nature of inter-atomic as well as intra-atomic hybridization of\u0000electrons, but also unbiased quantitative estimates of electrons on atoms or\u0000shared between them, as demonstrated in a select variety of isolated and\u0000periodic systems with varying degree of sharing of valence electrons among\u0000atoms, including variants of multi-centered bonds.","PeriodicalId":501211,"journal":{"name":"arXiv - PHYS - Other Condensed Matter","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141784199","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}
N. Kunchur, S. Galeski, F. Menges, R. Wawrzyńczak, C. Felser, T. Meng, J. Gooth
We analyze the transport properties of curved, three-dimensional graphite samples in strong magnetic fields. Focusing on a millimeter-scale graphite cylinder as a prototypical curved object, we perform longitudinal and Hall voltage measurements while applying quantizing magnetic fields. These measurements are investigated as a function of field strength and angles. Most importantly, we find that angle-dependent Shubnikov-de Hass oscillations are superimposed with angle-independent features. Reproducing the experimental observations, we introduce a network model that accounts for the cylindrical geometry effect by conceptualizing the cylinder as composed of strips of planar graphite in an effectively inhomogeneous magnetic field. Our work highlights how the interplay between geometric curvature and quantizing magnetic fields can be leveraged to engineer tunable spatial current densities within solid-state systems, and paves the way for understanding transport properties of curved and bent three-dimensional samples more generally.
{"title":"Magnetotransport in a graphite cylinder under quantizing fields","authors":"N. Kunchur, S. Galeski, F. Menges, R. Wawrzyńczak, C. Felser, T. Meng, J. Gooth","doi":"arxiv-2407.14263","DOIUrl":"https://doi.org/arxiv-2407.14263","url":null,"abstract":"We analyze the transport properties of curved, three-dimensional graphite\u0000samples in strong magnetic fields. Focusing on a millimeter-scale graphite\u0000cylinder as a prototypical curved object, we perform longitudinal and Hall\u0000voltage measurements while applying quantizing magnetic fields. These\u0000measurements are investigated as a function of field strength and angles. Most\u0000importantly, we find that angle-dependent Shubnikov-de Hass oscillations are\u0000superimposed with angle-independent features. Reproducing the experimental\u0000observations, we introduce a network model that accounts for the cylindrical\u0000geometry effect by conceptualizing the cylinder as composed of strips of planar\u0000graphite in an effectively inhomogeneous magnetic field. Our work highlights\u0000how the interplay between geometric curvature and quantizing magnetic fields\u0000can be leveraged to engineer tunable spatial current densities within\u0000solid-state systems, and paves the way for understanding transport properties\u0000of curved and bent three-dimensional samples more generally.","PeriodicalId":501211,"journal":{"name":"arXiv - PHYS - Other Condensed Matter","volume":"163 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141744832","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}
As a special type of collinear antiferromagnetism (AFM), altermagnetism has garnered significant research interest recently. Altermagnets exhibit broken parity-time symmetry and zero net magnetization in real space, leading to substantial band splitting in momentum space even in the absence of spin-orbit coupling. Meanwhile, parity-time symmetry breaking always induce nontrivial band topology such as Weyl nodes. While Weyl semimetal states and nodal lines have been theoretically proposed in altermagnets, rare reports of experimental observation have been made up to this point. Using ARPES and first-principles calculations, we systematically studied the electronic structure of the room-temperature altermagnet candidate CrSb. At generic locations in momentum space, we clearly observed band spin splitting. Furthermore, we identified discrete surface Fermi arcs on the (100) cleaved side surface close to the Fermi level originating from bulk band topology. Our results imply that CrSb contains interesting nontrivial topological Weyl physics, in addition to being an excellent room temperature altermagnet.
{"title":"Observation of surface Fermi arcs in altermagnetic Weyl semimetal CrSb","authors":"Wenlong Lu, Shiyu Feng, Yuzhi Wang, Dong Chen, Zihan Lin, Xin Liang, Siyuan Liu, Wanxiang Feng, Kohei Yamagami, Junwei Liu, Claudia Felser, Quansheng Wu, Junzhang Ma","doi":"arxiv-2407.13497","DOIUrl":"https://doi.org/arxiv-2407.13497","url":null,"abstract":"As a special type of collinear antiferromagnetism (AFM), altermagnetism has\u0000garnered significant research interest recently. Altermagnets exhibit broken\u0000parity-time symmetry and zero net magnetization in real space, leading to\u0000substantial band splitting in momentum space even in the absence of spin-orbit\u0000coupling. Meanwhile, parity-time symmetry breaking always induce nontrivial\u0000band topology such as Weyl nodes. While Weyl semimetal states and nodal lines\u0000have been theoretically proposed in altermagnets, rare reports of experimental\u0000observation have been made up to this point. Using ARPES and first-principles\u0000calculations, we systematically studied the electronic structure of the\u0000room-temperature altermagnet candidate CrSb. At generic locations in momentum\u0000space, we clearly observed band spin splitting. Furthermore, we identified\u0000discrete surface Fermi arcs on the (100) cleaved side surface close to the\u0000Fermi level originating from bulk band topology. Our results imply that CrSb\u0000contains interesting nontrivial topological Weyl physics, in addition to being\u0000an excellent room temperature altermagnet.","PeriodicalId":501211,"journal":{"name":"arXiv - PHYS - Other Condensed Matter","volume":"31 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141744640","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}
We study the influence of two mutual friction models on quantized vortices and normal fluid using two-way coupled simulations of superfluid $^4$He. The normal fluid is affected by quantized vortices via mutual friction. A previous study [Y. Tang, et al. Nat. Commun. 14, 2941 (2023)] compared the time evolutions of the vortex ring radius and determined that the self-consistent two-way coupled mutual friction (S2W) model yielded better agreement with the experimental results than the two-way coupled mutual friction (2W) model whose model parameters were determined through experiments with rotating superfluid helium. In this study, we compare the two models in more detail in terms of the quantized vortex ring propagation, reconnection, and thermal counterflow. We found that the S2W model exhibits better results than the 2W model on the microscopic scale near a quantized vortex, such as during quantized vortex ring propagation and reconnection, although the S2W model requires a higher spatial resolution. For complex flows such as a thermal counterflow, the 2W model can be applied even to a low-resolution flow while maintaining the anisotropic normal fluid velocity fluctuations. In contrast, the 2W model predicts lower normal fluid velocity fluctuations than the S2W model. The two models show probability density functions with $- 3$ power-law tails for the normal fluid velocity fluctuations.
{"title":"Influence of different mutual friction models on two-way coupled quantized vortices and normal fluid in superfluid $^4$He","authors":"Hiromichi Kobayashi, Satoshi Yui, Makoto Tsubota","doi":"arxiv-2407.12392","DOIUrl":"https://doi.org/arxiv-2407.12392","url":null,"abstract":"We study the influence of two mutual friction models on quantized vortices\u0000and normal fluid using two-way coupled simulations of superfluid $^4$He. The\u0000normal fluid is affected by quantized vortices via mutual friction. A previous\u0000study [Y. Tang, et al. Nat. Commun. 14, 2941 (2023)] compared the time\u0000evolutions of the vortex ring radius and determined that the self-consistent\u0000two-way coupled mutual friction (S2W) model yielded better agreement with the\u0000experimental results than the two-way coupled mutual friction (2W) model whose\u0000model parameters were determined through experiments with rotating superfluid\u0000helium. In this study, we compare the two models in more detail in terms of the\u0000quantized vortex ring propagation, reconnection, and thermal counterflow. We\u0000found that the S2W model exhibits better results than the 2W model on the\u0000microscopic scale near a quantized vortex, such as during quantized vortex ring\u0000propagation and reconnection, although the S2W model requires a higher spatial\u0000resolution. For complex flows such as a thermal counterflow, the 2W model can\u0000be applied even to a low-resolution flow while maintaining the anisotropic\u0000normal fluid velocity fluctuations. In contrast, the 2W model predicts lower\u0000normal fluid velocity fluctuations than the S2W model. The two models show\u0000probability density functions with $- 3$ power-law tails for the normal fluid\u0000velocity fluctuations.","PeriodicalId":501211,"journal":{"name":"arXiv - PHYS - Other Condensed Matter","volume":"163 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141744696","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}
Using a diffusion Monte Carlo (DMC) technique, we calculated the phase diagram of 3He adsorbed on a first solid layer of a molecular hydrogen isotope (H2,HD and D2) on top of graphite. The results are qualitatively similar in all cases: a two-dimensional gas spanning from the infinite dilution limit to a second-layer helium density of 0.048 +/- 0.004 Ang^{-2}. That gas is in equilibrium with a 7/12 commensurate structure, more stable than any incommensurate triangular solid of similar density. These findings are in reasonably good agreement with available experimental data.
{"title":"3He adsorbed on molecular hydrogen surfaces","authors":"M. C. Gordillo, J. Boronat","doi":"arxiv-2407.12436","DOIUrl":"https://doi.org/arxiv-2407.12436","url":null,"abstract":"Using a diffusion Monte Carlo (DMC) technique, we calculated the phase\u0000diagram of 3He adsorbed on a first solid layer of a molecular hydrogen isotope\u0000(H2,HD and D2) on top of graphite. The results are qualitatively similar in all\u0000cases: a two-dimensional gas spanning from the infinite dilution limit to a\u0000second-layer helium density of 0.048 +/- 0.004 Ang^{-2}. That gas is in\u0000equilibrium with a 7/12 commensurate structure, more stable than any\u0000incommensurate triangular solid of similar density. These findings are in\u0000reasonably good agreement with available experimental data.","PeriodicalId":501211,"journal":{"name":"arXiv - PHYS - Other Condensed Matter","volume":"70 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141744699","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}
M. E. Henderson, D. G. Cory, D. Sarenac, D. A. Pushin
Topological magnetism has sparked an unprecedented age in quantum technologies. Marked by twisted spin structures with exotic dynamical modes, topological magnets have motivated a new generation of spintronic devices which transcend the limits of conventional semiconductor-based electronics. While existing material probes have biased studies and device conceptualizations for thin samples in two dimensions, advancements in three-dimensional probing techniques using beams of neutrons, are transforming our understanding of topological and emergent physics to reimagine spintronic devices. Here, we review recent neutron scattering breakthroughs which harness quantum degrees of freedom to enable three-dimensional topological investigations of quantum materials. We discuss applications of structured and tomographic neutron scattering techniques to topological magnets, with particular emphasis on magnetic skyrmion systems and their inspired three-dimensional logic device infrastructures through novel multi-bit encoding and control schemes. SANS-based dynamic visualizations and coherent manipulations of three-dimensional topological qubits are proposed using electric field controls of depth-dependant helicities and spin-orbit tuning of the neutron beam. Together, these investigations uncover a new world of three-dimensional topological physics which enhances spintronic devices through a novel set of structures, dynamics, and controls, unique to three-dimensional systems.
{"title":"Quantum Advancements in Neutron Scattering Reshape Spintronic Devices","authors":"M. E. Henderson, D. G. Cory, D. Sarenac, D. A. Pushin","doi":"arxiv-2407.10822","DOIUrl":"https://doi.org/arxiv-2407.10822","url":null,"abstract":"Topological magnetism has sparked an unprecedented age in quantum\u0000technologies. Marked by twisted spin structures with exotic dynamical modes,\u0000topological magnets have motivated a new generation of spintronic devices which\u0000transcend the limits of conventional semiconductor-based electronics. While\u0000existing material probes have biased studies and device conceptualizations for\u0000thin samples in two dimensions, advancements in three-dimensional probing\u0000techniques using beams of neutrons, are transforming our understanding of\u0000topological and emergent physics to reimagine spintronic devices. Here, we\u0000review recent neutron scattering breakthroughs which harness quantum degrees of\u0000freedom to enable three-dimensional topological investigations of quantum\u0000materials. We discuss applications of structured and tomographic neutron\u0000scattering techniques to topological magnets, with particular emphasis on\u0000magnetic skyrmion systems and their inspired three-dimensional logic device\u0000infrastructures through novel multi-bit encoding and control schemes.\u0000SANS-based dynamic visualizations and coherent manipulations of\u0000three-dimensional topological qubits are proposed using electric field controls\u0000of depth-dependant helicities and spin-orbit tuning of the neutron beam.\u0000Together, these investigations uncover a new world of three-dimensional\u0000topological physics which enhances spintronic devices through a novel set of\u0000structures, dynamics, and controls, unique to three-dimensional systems.","PeriodicalId":501211,"journal":{"name":"arXiv - PHYS - Other Condensed Matter","volume":"33 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141722043","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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