Pub Date : 2024-08-29DOI: 10.1088/2515-7639/ad71f5
Christoph Sürgers, Gerda Fischer, Sihao Deng, Dongmei Hu, Cong Wang
Mn-based nitrides with antiperovskite structures have several properties that can be utilized for antiferromagnetic spintronics. Their magnetic properties depend on the structural quality, composition and doping of the cubic antiperovskite structure. Such nitride thin films are usually produced by reactive physical vapor deposition, where the deposition rate of N can only be controlled by the N2 gas flow. We show that the tuning of the N content can be optimized using low temperature resistivity measurements, which serve as an indicator of the degree of structural disorder. Several Mn3GaNx films were prepared by reactive magnetron sputtering under different N2 gas flows. Under optimized gas flow conditions, we obtain films that exhibit a metal-like temperature dependence of the resistivity, a vanishing logarithmic increase of the resistivity towards zero, the highest resistivity ratio, and a lattice contraction of 0.4% along the growth direction when heated above the Néel temperature TN. The retarded formation of an additional magnetic phase appearing at a temperature T∗≪TN gives rise to a large thermal hysteresis of the resistivity and anomalous Hall effect.
具有反包晶石结构的锰基氮化物具有多种特性，可用于反铁磁自旋电子学。它们的磁性取决于立方反钝化结构的结构质量、组成和掺杂。这种氮化物薄膜通常是通过反应性物理气相沉积法生产的，其中 N 的沉积速率只能通过 N2 气体流量来控制。我们的研究表明，可以通过低温电阻率测量来优化 N 含量的调整，这可以作为结构紊乱程度的指标。我们在不同的 N2 气体流条件下通过反应磁控溅射制备了几种 Mn3GaNx 薄膜。在优化的气流条件下，我们获得的薄膜表现出类似金属的电阻率温度依赖性、电阻率向零的对数增长消失、最高的电阻率比，以及当加热超过奈尔温度 TN 时沿生长方向 0.4% 的晶格收缩。在温度 T∗≪TN 时出现的附加磁性相的延迟形成导致了电阻率的巨大热滞后和反常霍尔效应。
{"title":"Electronic transport in reactively sputtered Mn3GaN films prepared under optimized nitrogen flow","authors":"Christoph Sürgers, Gerda Fischer, Sihao Deng, Dongmei Hu, Cong Wang","doi":"10.1088/2515-7639/ad71f5","DOIUrl":"https://doi.org/10.1088/2515-7639/ad71f5","url":null,"abstract":"Mn-based nitrides with antiperovskite structures have several properties that can be utilized for antiferromagnetic spintronics. Their magnetic properties depend on the structural quality, composition and doping of the cubic antiperovskite structure. Such nitride thin films are usually produced by reactive physical vapor deposition, where the deposition rate of N can only be controlled by the N<sub>2</sub> gas flow. We show that the tuning of the N content can be optimized using low temperature resistivity measurements, which serve as an indicator of the degree of structural disorder. Several Mn<sub>3</sub>GaN<sub><italic toggle=\"yes\">x</italic></sub> films were prepared by reactive magnetron sputtering under different N<sub>2</sub> gas flows. Under optimized gas flow conditions, we obtain films that exhibit a metal-like temperature dependence of the resistivity, a vanishing logarithmic increase of the resistivity towards zero, the highest resistivity ratio, and a lattice contraction of 0.4% along the growth direction when heated above the Néel temperature <inline-formula>\u0000<tex-math><?CDATA $T_textrm{N}$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:msub><mml:mi>T</mml:mi><mml:mtext>N</mml:mtext></mml:msub></mml:mrow></mml:math><inline-graphic xlink:href=\"jpmaterad71f5ieqn1.gif\"></inline-graphic></inline-formula>. The retarded formation of an additional magnetic phase appearing at a temperature <inline-formula>\u0000<tex-math><?CDATA $T^{ast} ll T_textrm{N}$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:msup><mml:mi>T</mml:mi><mml:mrow><mml:mo>∗</mml:mo></mml:mrow></mml:msup><mml:mo>≪</mml:mo><mml:msub><mml:mi>T</mml:mi><mml:mtext>N</mml:mtext></mml:msub></mml:mrow></mml:math><inline-graphic xlink:href=\"jpmaterad71f5ieqn2.gif\"></inline-graphic></inline-formula> gives rise to a large thermal hysteresis of the resistivity and anomalous Hall effect.","PeriodicalId":501825,"journal":{"name":"Journal of Physics: Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142178185","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 : 2024-08-14DOI: 10.1088/2515-7639/ad6c7f
Cunyuan Jiang, Giovanni Alberto Ummarino, Matteo Baggioli, Efthymios Liarokapis, Alessio Zaccone
We provide a mathematical description, based on d-wave Eliashberg theory, of the strong correlation between the experimentally observed softening of Raman modes associated with in-plane oxygen motions and the corresponding superconducting critical temperature Tc, as a function of oxygen doping x, in YBa2Cu3Ox. The theoretical model provides a direct link between physical trends of soft optical Ag (in-plane) oxygen modes, the level of oxygen doping x, and the superconducting Tc. Different regimes observed in the trend of Tc vs doping can be related to corresponding regimes of optical phonon softening in the Raman spectra. These results provide further evidence related to the physical origin of high-temperature superconductivity in rare-earth cuprate oxides and to the significant role of electron–phonon coupling therein.
在 YBa2Cu3Ox 中，实验观察到的与面内氧运动相关的拉曼模式软化与相应的超导临界温度 Tc 之间存在很强的相关性，而这是氧掺杂 x 的函数，我们根据 d 波埃利亚什伯格理论对这一现象进行了数学描述。该理论模型提供了软光学 Ag（面内）氧模式的物理趋势、氧掺杂水平 x 和超导临界温度 Tc 之间的直接联系。在 Tc 与掺杂趋势中观察到的不同状态可与拉曼光谱中光学声子软化的相应状态联系起来。这些结果为稀土铜氧化物高温超导的物理起源以及电子-声子耦合在其中的重要作用提供了进一步的证据。
{"title":"Correlation between optical phonon softening and superconducting Tc in YBa2Cu3Ox within d-wave Eliashberg theory","authors":"Cunyuan Jiang, Giovanni Alberto Ummarino, Matteo Baggioli, Efthymios Liarokapis, Alessio Zaccone","doi":"10.1088/2515-7639/ad6c7f","DOIUrl":"https://doi.org/10.1088/2515-7639/ad6c7f","url":null,"abstract":"We provide a mathematical description, based on <italic toggle=\"yes\">d</italic>-wave Eliashberg theory, of the strong correlation between the experimentally observed softening of Raman modes associated with in-plane oxygen motions and the corresponding superconducting critical temperature <inline-formula>\u0000<tex-math><?CDATA $T_mathrm{c}$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:msub><mml:mi>T</mml:mi><mml:mrow><mml:mi mathvariant=\"normal\">c</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math><inline-graphic xlink:href=\"jpmaterad6c7fieqn2.gif\"></inline-graphic></inline-formula>, as a function of oxygen doping <italic toggle=\"yes\">x</italic>, in YBa<sub>2</sub>Cu<sub>3</sub>O<sub><italic toggle=\"yes\">x</italic></sub>. The theoretical model provides a direct link between physical trends of soft optical <italic toggle=\"yes\">A<sub>g</sub></italic> (in-plane) oxygen modes, the level of oxygen doping <italic toggle=\"yes\">x</italic>, and the superconducting <inline-formula>\u0000<tex-math><?CDATA $T_mathrm{c}$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:msub><mml:mi>T</mml:mi><mml:mrow><mml:mi mathvariant=\"normal\">c</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math><inline-graphic xlink:href=\"jpmaterad6c7fieqn3.gif\"></inline-graphic></inline-formula>. Different regimes observed in the trend of <inline-formula>\u0000<tex-math><?CDATA $T_mathrm{c}$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:msub><mml:mi>T</mml:mi><mml:mrow><mml:mi mathvariant=\"normal\">c</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math><inline-graphic xlink:href=\"jpmaterad6c7fieqn4.gif\"></inline-graphic></inline-formula> vs doping can be related to corresponding regimes of optical phonon softening in the Raman spectra. These results provide further evidence related to the physical origin of high-temperature superconductivity in rare-earth cuprate oxides and to the significant role of electron–phonon coupling therein.","PeriodicalId":501825,"journal":{"name":"Journal of Physics: Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142178190","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 : 2024-08-11DOI: 10.1088/2515-7639/ad6930
S Duston, R A Oliver, K J Kubiak, Y Wang, C Wang and A Morina
3D Tribo-Nanoprinting (3D TNP), which uses a highly controllable tribological contact to deposit tribofilms, has been proposed as a manufacturing method for nanoscale structures. Inspired by this, we show for the first time, as a proof of concept, the ability to electrically functionalise tribofilms for potential use in the manufacture of structures with nanoscale thickness. Zinc dialkyldithiophosphate (ZDDP) tribofilms have been generated to include varying concentrations of graphene nanoplatelets (GNPs) resulting in them becoming electrically conductive when tested using conductive atomic force microscopy. In its highest GNP concentration, approximately 55% of the surface of the tribofilm was able to sustain current up to a threshold of 245 pA. The higher graphene content led to a suppression in film formation and decreased substrate coverage. Transmission electron microscopy revealed a dual-layered tribofilm with a carbon-rich layer above a pure layer of ZDDP tribofilm. Within the carbon-rich layer, the GNPs formed into scrolls which created an internal network through which current could flow, being limited by the insulating pure ZDDP layer at the film-substrate interface, and the presence of surface graphene sheets. A modified lateral force microscopy procedure supported the presence of surface graphene sheets. Despite limited deposition precision in terms of homogeneity and distribution of the tribofilms, this work provides a step towards the use of 3D TNP for the manufacture of electronic structures on the nanoscale by proving that tribofilms can be functionalised by the addition of particle additives.
{"title":"Tribological manufacturing of ZDDP tribofilms functionalised by graphene nanoplatelets","authors":"S Duston, R A Oliver, K J Kubiak, Y Wang, C Wang and A Morina","doi":"10.1088/2515-7639/ad6930","DOIUrl":"https://doi.org/10.1088/2515-7639/ad6930","url":null,"abstract":"3D Tribo-Nanoprinting (3D TNP), which uses a highly controllable tribological contact to deposit tribofilms, has been proposed as a manufacturing method for nanoscale structures. Inspired by this, we show for the first time, as a proof of concept, the ability to electrically functionalise tribofilms for potential use in the manufacture of structures with nanoscale thickness. Zinc dialkyldithiophosphate (ZDDP) tribofilms have been generated to include varying concentrations of graphene nanoplatelets (GNPs) resulting in them becoming electrically conductive when tested using conductive atomic force microscopy. In its highest GNP concentration, approximately 55% of the surface of the tribofilm was able to sustain current up to a threshold of 245 pA. The higher graphene content led to a suppression in film formation and decreased substrate coverage. Transmission electron microscopy revealed a dual-layered tribofilm with a carbon-rich layer above a pure layer of ZDDP tribofilm. Within the carbon-rich layer, the GNPs formed into scrolls which created an internal network through which current could flow, being limited by the insulating pure ZDDP layer at the film-substrate interface, and the presence of surface graphene sheets. A modified lateral force microscopy procedure supported the presence of surface graphene sheets. Despite limited deposition precision in terms of homogeneity and distribution of the tribofilms, this work provides a step towards the use of 3D TNP for the manufacture of electronic structures on the nanoscale by proving that tribofilms can be functionalised by the addition of particle additives.","PeriodicalId":501825,"journal":{"name":"Journal of Physics: Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141936264","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 : 2024-08-08DOI: 10.1088/2515-7639/ad6cf6
V. Gargiulo, Roberto Di Capua, M. Vorochta, G. Aquilanti, Tomáš Skála, Claudio Clemente, M. Alfè
Hybrids based on the copper-based metal-organic framework (MOF) HKUST-1 and graphene-like (GL) materials have been synthesized at different concentrations of GL, and investigated by means of solid state nuclear magnetic resonance (ssNMR) and X-rays absorption techniques (NEXAFS and XANES) with the aim of elucidating the effect of the hybridization on the structural properties of HKUST-1. The comparative analysis of ssNMR and X-ray absorption spectra recorded on parent materials (GL materials and pure HKUST-1) and on the hybrids indicates that the overall structural features of HKUST-1 are preserved in the presence of increasing GL amounts (up to 30 wt.%) and confirms that the framework development is not massively altered by the presence of GRMs in the synthetic medium.
研究人员合成了不同浓度的铜基金属有机框架（MOF）HKUST-1 和类石墨烯（GL）材料的杂化物，并通过固态核磁共振（ssNMR）和 X 射线吸收技术（NEXAFS 和 XANES）进行了研究，旨在阐明杂化对 HKUST-1 结构特性的影响。对记录在母体材料（GL 材料和纯香港科技大学-1）和杂交体上的 ssNMR 和 X 射线吸收光谱进行的比较分析表明，香港科技大学-1 的总体结构特征在 GL 含量增加（最多 30 wt.%）的情况下得以保留，并证实合成介质中 GRM 的存在不会大规模改变框架的发展。
{"title":"Insights about the effect of metal-organic framework hybridization with graphene-like materials","authors":"V. Gargiulo, Roberto Di Capua, M. Vorochta, G. Aquilanti, Tomáš Skála, Claudio Clemente, M. Alfè","doi":"10.1088/2515-7639/ad6cf6","DOIUrl":"https://doi.org/10.1088/2515-7639/ad6cf6","url":null,"abstract":"\u0000 Hybrids based on the copper-based metal-organic framework (MOF) HKUST-1 and graphene-like (GL) materials have been synthesized at different concentrations of GL, and investigated by means of solid state nuclear magnetic resonance (ssNMR) and X-rays absorption techniques (NEXAFS and XANES) with the aim of elucidating the effect of the hybridization on the structural properties of HKUST-1. The comparative analysis of ssNMR and X-ray absorption spectra recorded on parent materials (GL materials and pure HKUST-1) and on the hybrids indicates that the overall structural features of HKUST-1 are preserved in the presence of increasing GL amounts (up to 30 wt.%) and confirms that the framework development is not massively altered by the presence of GRMs in the synthetic medium.","PeriodicalId":501825,"journal":{"name":"Journal of Physics: Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141927273","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 : 2024-07-18DOI: 10.1088/2515-7639/ad5c06
Arefin Mustafa Anik, Vaibhav Palkar, Igor Luzinov and Olga Kuksenok
Polyolefins account for more than half of global primary polymer production, however only a small fraction of these polymers are currently being recycled. Fragmentation of polymer chains into shorter chains with a targeted molecular weight distribution with the goal of reusing these fragments in subsequent chemical synthesis can potentially introduce an alternative approach to polyolefins recycling. Herein we develop a mesoscale framework to model degradation of polyethylene melts at a range of high temperatures. We use the dissipative particle dynamics approach with modified segmental repulsive potential to model the process of random scission in melts of linear polymer chains. We characterize the fragmentation process by tracking the time evolution of the distribution of degrees of polymerization of chain fragments. Specifically, we track the weight average and the number average degrees of polymerization and dispersity of polymer fragments as a function of the fraction of bonds broken. Furthermore, we track the number fraction distribution and the weight fraction distribution of polymer fragments with various degrees of polymerization as functions of the fraction of bonds broken for a range of high temperatures. Our results allow one to quantify to what extent the distribution of polymer chain fragments during random scission can be captured by the respective analytical distributions for the range of conversions considered. Understanding the thermal degradation of polyolefins on the mesoscale can result in the development of alternative strategies for recycling a range of thermoplastics.
{"title":"Mesoscale modeling of random chain scission in polyethylene melts","authors":"Arefin Mustafa Anik, Vaibhav Palkar, Igor Luzinov and Olga Kuksenok","doi":"10.1088/2515-7639/ad5c06","DOIUrl":"https://doi.org/10.1088/2515-7639/ad5c06","url":null,"abstract":"Polyolefins account for more than half of global primary polymer production, however only a small fraction of these polymers are currently being recycled. Fragmentation of polymer chains into shorter chains with a targeted molecular weight distribution with the goal of reusing these fragments in subsequent chemical synthesis can potentially introduce an alternative approach to polyolefins recycling. Herein we develop a mesoscale framework to model degradation of polyethylene melts at a range of high temperatures. We use the dissipative particle dynamics approach with modified segmental repulsive potential to model the process of random scission in melts of linear polymer chains. We characterize the fragmentation process by tracking the time evolution of the distribution of degrees of polymerization of chain fragments. Specifically, we track the weight average and the number average degrees of polymerization and dispersity of polymer fragments as a function of the fraction of bonds broken. Furthermore, we track the number fraction distribution and the weight fraction distribution of polymer fragments with various degrees of polymerization as functions of the fraction of bonds broken for a range of high temperatures. Our results allow one to quantify to what extent the distribution of polymer chain fragments during random scission can be captured by the respective analytical distributions for the range of conversions considered. Understanding the thermal degradation of polyolefins on the mesoscale can result in the development of alternative strategies for recycling a range of thermoplastics.","PeriodicalId":501825,"journal":{"name":"Journal of Physics: Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141741508","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 : 2024-07-16DOI: 10.1088/2515-7639/ad63cb
Victor Caliva, J. I. Fuks
Many quantum phenomena responsible for key applications in material science and quantum chemistry arise in the strongly correlated regime. This is at the same time, a costly regime for computer simulations. In the limit of strong correlation analytic solutions exist, but as we move away from this limit numerical simulation are needed, and accurate quantum solutions do not scale well with the number of interacting particles. In this work we propose to use few-particle harmonic traps in combination with twisted light as a quantum emulator to investigate the transition into a strongly-correlated regime. Using both analytic derivations and numerical simulations we generalize previous findings on 2 Coulomb interacting fermions trapped in a one-dimensional harmonic trap to the case of 3 fermions. The 4 signatures of strong correlation we have identified in the one- dimensional harmonic trap are: i) the ground state density is highly localized around N equilibrium positions, where N is the number of particles, ii) the symmetric and antisymmetric ground state wavefunctions become degenerate, iii) the von Neumann entropy grows, iv) the energy spectrum is fully characterized by N normal modes or less. Our findings describe the low-energy behavior of electrons in quantum wires and ions in Paul traps. Similar features have also been reported for cold atoms in optical lattices.
在材料科学和量子化学的关键应用领域中，许多量子现象都产生于强相关体系。同时，这也是计算机模拟的高成本体系。在强相关极限存在解析解，但当我们远离这个极限时，就需要进行数值模拟，而精确的量子解并不能很好地与相互作用粒子的数量相匹配。在这项工作中，我们提议使用少粒子谐波陷阱结合扭曲光作为量子仿真器，研究向强相关机制的过渡。通过分析推导和数值模拟，我们将之前对被困在一维谐波陷阱中的 2 个库仑相互作用费米子的研究结果推广到 3 个费米子的情况。我们在一维谐波陷阱中发现的强相关性的 4 个特征是：i) 基态密度在 N 个平衡位置附近高度局域化，其中 N 是粒子数；ii) 对称和非对称基态波函数变得退化；iii) 冯-诺依曼熵增长；iv) 能谱完全由 N 个或更少的法向模态表征。我们的发现描述了量子线中电子和保罗陷阱中离子的低能行为。光晶格中冷原子的类似特征也有报道。
{"title":"Characteristic features of strong correlation: lessons from a 3-fermionone-dimensional harmonic trap","authors":"Victor Caliva, J. I. Fuks","doi":"10.1088/2515-7639/ad63cb","DOIUrl":"https://doi.org/10.1088/2515-7639/ad63cb","url":null,"abstract":"\u0000 Many quantum phenomena responsible for key applications in material science and quantum chemistry arise in the strongly correlated regime. This is at the same time, a costly regime for computer simulations. In the limit of strong correlation analytic solutions exist, but as we move away from this limit numerical simulation are needed, and accurate quantum solutions do not scale well with the number of interacting particles. In this work we propose to use few-particle harmonic traps in combination with twisted light as a quantum emulator to investigate the transition into a strongly-correlated regime. Using both analytic derivations and numerical simulations we generalize previous findings on 2 Coulomb interacting fermions trapped in a one-dimensional harmonic trap to the case of 3 fermions. The 4 signatures of strong correlation we have identified in the one- dimensional harmonic trap are: i) the ground state density is highly localized around N equilibrium positions, where N is the number of particles, ii) the symmetric and antisymmetric ground state wavefunctions become degenerate, iii) the von Neumann entropy grows, iv) the energy spectrum is fully characterized by N normal modes or less. Our findings describe the low-energy behavior of electrons in quantum wires and ions in Paul traps. Similar features have also been reported for cold atoms in optical lattices.","PeriodicalId":501825,"journal":{"name":"Journal of Physics: Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141641281","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 : 2024-07-11DOI: 10.1088/2515-7639/ad5ec1
Sergey Grebenchuk, Magdalena Grzeszczyk, Zhaolong Chen, Kostya S Novoselov and Maciej Koperski
Two-dimensional materials provide with ability to control their properties with a number of methods. One of such methods is using strain and compression. In this work, we investigated the influence of locally induced strain through bubbles in thin ferromagnetic CrBr3 using low-temperature magnetic force microscopy. As a result, domain pinning and higher coercive and saturation fields were observed in the bubble. In addition, nontrivial spin arrangements are allowed to take place in a non-homogeneously strained area, leading to different responses to the external magnetic field in comparison to a non-strained region. Finally, Raman spectroscopy and magneto-photoluminescence spectroscopy were performed to show alternation of the magnetic properties of the sample under mechanical deformation.
{"title":"Effects of bubble-induced strain on the magnetic properties of van der Waals ferromagnet CrBr3","authors":"Sergey Grebenchuk, Magdalena Grzeszczyk, Zhaolong Chen, Kostya S Novoselov and Maciej Koperski","doi":"10.1088/2515-7639/ad5ec1","DOIUrl":"https://doi.org/10.1088/2515-7639/ad5ec1","url":null,"abstract":"Two-dimensional materials provide with ability to control their properties with a number of methods. One of such methods is using strain and compression. In this work, we investigated the influence of locally induced strain through bubbles in thin ferromagnetic CrBr3 using low-temperature magnetic force microscopy. As a result, domain pinning and higher coercive and saturation fields were observed in the bubble. In addition, nontrivial spin arrangements are allowed to take place in a non-homogeneously strained area, leading to different responses to the external magnetic field in comparison to a non-strained region. Finally, Raman spectroscopy and magneto-photoluminescence spectroscopy were performed to show alternation of the magnetic properties of the sample under mechanical deformation.","PeriodicalId":501825,"journal":{"name":"Journal of Physics: Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141610601","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 : 2024-07-10DOI: 10.1088/2515-7639/ad618e
Matthias Prasch, Roland Wuerschum, S. Topolovec
A nanocomposite consisting of iron disilicide nanocrystals embedded in a Si matrix was prepared from industry-grade ferrosilicon by ball milling and subsequent heat treatment. By tailoring the heat treatment temperature either the metallic α-FeSi2 or the semiconducting β-FeSi2 phase could be made the dominant one, as indicated by X-ray diffraction. Magnetization curve and zero-field cooled/field cooled measurements revealed that ferromagnetic and superparamagnetic centers are present in the nanocomposites, which could be attributed to Fe-rich defective regions at the surface of the iron disilicide nanocrystals. For both nanocomposites, containing either mainly the α or β phase, we could show that the magnetization can be varied by about 40% by electrochemical lithiation and delithiation of the surrounding Si matrix, with up to 6.5% of the magnetization change beingreversible. These variations could be attributed to the formation of additional Fe-rich magnetic regions, induced by a local change of the Fe/Si fraction at the FeSi2/Si interfaces, and their subsequent partial elimination. Thus, this work demonstrates a new concept for how an "indirect magneto-ionic effect'' can be obtained in composite materials consisting of a phase prone to the electrochemical ion uptake (i.e., the Si matrix) and a magnetic phase (i.e., the FeSi2 nanocrystals).
{"title":"Indirect magneto-ionic effect in FeSi2/Si nanocomposite induced by electrochemical lithiation and delithiation","authors":"Matthias Prasch, Roland Wuerschum, S. Topolovec","doi":"10.1088/2515-7639/ad618e","DOIUrl":"https://doi.org/10.1088/2515-7639/ad618e","url":null,"abstract":"\u0000 A nanocomposite consisting of iron disilicide nanocrystals embedded in a Si matrix was prepared from industry-grade ferrosilicon by ball milling and subsequent heat treatment. By tailoring the heat treatment temperature either the metallic α-FeSi2 or the semiconducting β-FeSi2 phase could be made the dominant one, as indicated by X-ray diffraction. Magnetization curve and zero-field cooled/field cooled measurements revealed that ferromagnetic and superparamagnetic centers are present in the nanocomposites, which could be attributed to Fe-rich defective regions at the surface of the iron disilicide nanocrystals. For both nanocomposites, containing either mainly the α or β phase, we could show that the magnetization can be varied by about 40% by electrochemical lithiation and delithiation of the surrounding Si matrix, with up to 6.5% of the magnetization change beingreversible. These variations could be attributed to the formation of additional Fe-rich magnetic regions, induced by a local change of the Fe/Si fraction at the FeSi2/Si interfaces, and their subsequent partial elimination. Thus, this work demonstrates a new concept for how an \"indirect magneto-ionic effect'' can be obtained in composite materials consisting of a phase prone to the electrochemical ion uptake (i.e., the Si matrix) and a magnetic phase (i.e., the FeSi2 nanocrystals).","PeriodicalId":501825,"journal":{"name":"Journal of Physics: Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141660843","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 : 2024-07-10DOI: 10.1088/2515-7639/ad618d
Sina Zare Pakzad, M. Nasr Esfahani, B. E. Alaca
Silicon nanowires entail significant potential as sensors in nanoelectromechanical systems. Despite its crucial impact in such applications, inconsistent trends in mechanical behavior reported in computational and experimental studies remain unexplained. Hence, scale effect in even the most fundamental elastic properties requires clarification. This work introduces a multiscale model to bridge the existing gap between atomistic simulations and experimental observations encountered around a critical dimension of 10 nm. The combined approach of this work is based on molecular dynamics and modified core-shell model and captures the scale effect over a substantial size range. The evolution of the modulus of elasticity is thus studied and linked to nanowire critical dimension through the parameterization of surface inhomogeneity. The developed method is also validated through an analysis of native oxide revealing an average modulus of elasticity of 75 GPa. The method’s applicability can be extended to similar one-dimensional structures with unique surface states.
{"title":"An analytical-atomistic model for elastic behavior of silicon nanowires","authors":"Sina Zare Pakzad, M. Nasr Esfahani, B. E. Alaca","doi":"10.1088/2515-7639/ad618d","DOIUrl":"https://doi.org/10.1088/2515-7639/ad618d","url":null,"abstract":"\u0000 Silicon nanowires entail significant potential as sensors in nanoelectromechanical systems. Despite its crucial impact in such applications, inconsistent trends in mechanical behavior reported in computational and experimental studies remain unexplained. Hence, scale effect in even the most fundamental elastic properties requires clarification. This work introduces a multiscale model to bridge the existing gap between atomistic simulations and experimental observations encountered around a critical dimension of 10 nm. The combined approach of this work is based on molecular dynamics and modified core-shell model and captures the scale effect over a substantial size range. The evolution of the modulus of elasticity is thus studied and linked to nanowire critical dimension through the parameterization of surface inhomogeneity. The developed method is also validated through an analysis of native oxide revealing an average modulus of elasticity of 75 GPa. The method’s applicability can be extended to similar one-dimensional structures with unique surface states.","PeriodicalId":501825,"journal":{"name":"Journal of Physics: Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141659576","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 : 2024-07-03DOI: 10.1088/2515-7639/ad5c05
Mario Ibrahin Gutierrez, Pathikumar Sellappan, Elias H Penilla, Irais Poblete-Naredo, Arturo Vera, Lorenzo Leija and Javier E Garay
Therapeutic ultrasound for brain stimulation has increased in the last years. This energy has shown promising results for treating Alzheimer’s disease, Parkinson’s disease and traumatic brain injury, among other conditions. However, the application of ultrasound in the brain should trespass a natural but highly attenuating and distorting barrier, the cranium. Implantable ceramic materials can be used to replace part of the cranium as an alternate method to enhance ultrasound transmission. In this work, it is presented the acoustic characterization of alumina ceramic disks that can be employed as cranial implants for acoustic windows-to-the-brain. Alumina samples were prepared using current-activated pressure-assisted densification and were acoustically characterized. Acoustic impedance and attenuation of the samples were determined for different porosities. Additionally, measured and modeled acoustic fields are presented and analyzed in terms of the total ultrasound transmitted through the ceramics. Results indicate a resonant behavior in the alumina disks when the thickness corresponds to a half-wavelength of ultrasound; this resonance permits a total of 95.4% of ultrasound transmission; for thicknesses out of the resonant zone, transmission is 53.0%. Alumina proves to be an excellent medium for ultrasound transmission that, in conjunction with its mechanical and optical properties, can be useful for cranium replacement in mixed opto-acoustic applications.
{"title":"Acoustically transparent alumina-based cranial implants enhance ultrasound transmission through a combined mechano-acoustic resonant effect","authors":"Mario Ibrahin Gutierrez, Pathikumar Sellappan, Elias H Penilla, Irais Poblete-Naredo, Arturo Vera, Lorenzo Leija and Javier E Garay","doi":"10.1088/2515-7639/ad5c05","DOIUrl":"https://doi.org/10.1088/2515-7639/ad5c05","url":null,"abstract":"Therapeutic ultrasound for brain stimulation has increased in the last years. This energy has shown promising results for treating Alzheimer’s disease, Parkinson’s disease and traumatic brain injury, among other conditions. However, the application of ultrasound in the brain should trespass a natural but highly attenuating and distorting barrier, the cranium. Implantable ceramic materials can be used to replace part of the cranium as an alternate method to enhance ultrasound transmission. In this work, it is presented the acoustic characterization of alumina ceramic disks that can be employed as cranial implants for acoustic windows-to-the-brain. Alumina samples were prepared using current-activated pressure-assisted densification and were acoustically characterized. Acoustic impedance and attenuation of the samples were determined for different porosities. Additionally, measured and modeled acoustic fields are presented and analyzed in terms of the total ultrasound transmitted through the ceramics. Results indicate a resonant behavior in the alumina disks when the thickness corresponds to a half-wavelength of ultrasound; this resonance permits a total of 95.4% of ultrasound transmission; for thicknesses out of the resonant zone, transmission is 53.0%. Alumina proves to be an excellent medium for ultrasound transmission that, in conjunction with its mechanical and optical properties, can be useful for cranium replacement in mixed opto-acoustic applications.","PeriodicalId":501825,"journal":{"name":"Journal of Physics: Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141550884","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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