Pub Date : 2022-02-17DOI: 10.3389/femat.2022.878308
K. Avers, W. Gannon, A. Leishman, L. Debeer-Schmitt, W. Halperin, M. Eskildsen
We have used small-angle neutron scattering to determine the vortex lattice phase diagram in the topological superconductor UPt3 for the applied magnetic field along the crystalline c-axis. A triangular vortex lattice is observed throughout the superconducting state, but with an orientation relative to the hexagonal basal plane that changes with field and temperature. At low temperature, in the chiral B phase, the vortex lattice undergoes a non-monotonic rotation with increasing magnetic field. The rotation amplitude decreases with increasing temperature and vanishes before reaching the A phase. Within the A phase an abrupt ±15° vortex lattice rotation was previously reported by Huxley et al., Nature 406, 160-164 (2000). The complex phase diagram may be understood from competing effects of the superconducting order parameter, the symmetry breaking field, and the Fermi surface anisotropy. The low-temperature rotated phase, centered around 0.8 T, reported by Avers et al., Nature Physics 16, 531-535 (2020), can be attributed directly to the symmetry breaking field.
我们利用小角中子散射法确定了拓扑超导体UPt3在外加磁场作用下沿晶体c轴的涡点阵相图。在整个超导态中观察到一个三角形涡晶格，但其取向相对于六边形基底面，随场和温度的变化而变化。在低温下，在手性B相中，涡旋晶格随着磁场的增大而发生非单调旋转。旋转振幅随温度升高而减小，在到达A相之前消失。在A相中，Huxley等人在Nature 406, 160-164(2000)中报道了±15°旋涡晶格的突然旋转。复相图可以从超导序参量、对称破缺场和费米表面各向异性的竞争效应来理解。由Avers et al.， Nature Physics 16, 531-535(2020)报道的以0.8 T为中心的低温旋转相位可以直接归因于对称破缺场。
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Pub Date : 2021-07-20DOI: 10.3389/femat.2021.677845
Peter A. Finn, Ceyla Asker, K. Wan, E. Bilotti, O. Fenwick, C. Nielsen
Net zero refers to the balance of the amount of greenhouse gas emissions produced and the amount removed from the atmosphere, and many companies and states have committed themselves to net zero targets. In June 2019, the United Kingdom became the first major economy in the world to pass a net zero emissions law. This ambitious target aims to reduce the UK’s net emissions of greenhouse gases by 100 per cent relative to 1,990 levels by 2,050 and replaces the UK’s previous target to reduce emissions by at least 80%. Sweden, France, Denmark, New Zealand and Hungary have also now succeeded in putting net zero targets into law (Net Zero Emissions Race, 2020). Progress towards these net zero goals has so far been slow. For example, the United Kingdom is behind on even the original 80% target, and achieving the current aim by 2,050 will be challenging. One thing that is clear to the scientific community is that improvements in technology between now and 2,050 will be key to bring the net zero target within reach. However, this will only happen if we can identify technologies for accelerated development and invest in them now, so we can deliver benefits before the 2,050 deadline. There are multiple areas where new technologies can assist in energy generation and storage, including photovoltaics, wind and water turbines, the hydrogen economy, caloric materials and batteries, as well as energy saving technologies such as low loss electronics. Thermoelectric energy conversion materials were identified by the Henry Royce Institute and the Institute of Physics as a key area of materials research for achieving net zero emissions in the Materials for the Energy Transition (2019) report. Space heating and cooling (e.g., central heating or air conditioning), is one of the main contributors to emissions and accounts for around 17% of the UK’s CO2 emissions (Department for Business, Energy and industrial Strategy, 2018). In Saudi Arabia, one of the hottest and driest countries in the world, more than 70% of the kingdom’s electricity produced per year is consumed purely for air conditioning and cooling purposes, with the demand doubling during the summer (Demirbas et al., 2017). This home water and space heating is typically achieved through burning natural gas in countries with access to natural gas, and through electrically-powered airsource heat pumps elsewhere. More widespread deployment of air-source heat pumps creates increased electricity demand, so solar-integrated heat pumps are also being investigated as another potential alternative to meet current space heating and domestic hot water demands with a reduced draw from the grid. However, these pumps use refrigerants such as HFCs, which are powerful greenhouse gases, so heat pumps that use other types of materials, such as thermoelectric and caloric materials need to be investigated as “greener” options. Thermoelectric materials use temperature differences to generate electrical energy. They can therefore pro
净零指的是产生的温室气体排放量与从大气中去除的温室气体排放量之间的平衡，许多公司和州已经承诺实现净零目标。2019年6月，英国成为世界上第一个通过净零排放法的主要经济体。这一雄心勃勃的目标旨在到2050年将英国的温室气体净排放量相对于1990年的水平减少100%，并取代英国之前减少排放量至少80%的目标。瑞典、法国、丹麦、新西兰和匈牙利现在也成功地将净零排放目标写入法律(净零排放竞赛，2020年)。迄今为止，实现这些净零目标的进展缓慢。例如，英国甚至落后于最初的80%的目标，到2050年实现目前的目标将是具有挑战性的。科学界很清楚的一点是，从现在到2050年，技术进步将是实现净零排放目标的关键。然而，这只有在我们能够确定加速发展的技术并现在就对其进行投资的情况下才能实现，这样我们才能在2050年的最后期限之前实现效益。新技术可以在多个领域协助能源生产和储存，包括光伏发电、风力和水力涡轮机、氢经济、发热材料和电池，以及低损耗电子等节能技术。在《能源转型材料(2019)》报告中，亨利·罗伊斯研究所和物理研究所将热电能量转换材料确定为实现净零排放的材料研究的关键领域。空间供暖和制冷(如中央供暖或空调)是排放的主要来源之一，约占英国二氧化碳排放量的17%(商业、能源和工业战略部，2018年)。沙特阿拉伯是世界上最热和最干燥的国家之一，该国每年生产的电力中有70%以上纯粹用于空调和制冷目的，夏季需求翻倍(Demirbas et al.， 2017)。这种家庭用水和空间供暖通常是通过在拥有天然气的国家燃烧天然气来实现的，而在其他地方则通过电动空气源热泵来实现。空气源热泵的更广泛部署会增加电力需求，因此太阳能集成热泵也正在被研究，作为另一种潜在的替代方案，以满足当前的空间供暖和家庭热水需求，同时减少从电网的消耗。然而，这些泵使用氢氟碳化物等制冷剂，这是一种强大的温室气体，因此使用其他类型材料的热泵，如热电材料和热材料，需要作为“更环保”的选择进行研究。热电材料利用温差产生电能。因此，它们可以提供全电加热和冷却技术，而不需要移动部件或制冷剂。这项技术的另一个优点是，它可以用来收集其他过程产生的废热，并将其直接转化为电能。由于大约三分之二的一次能源被浪费为热能(美国劳伦斯利弗莫尔国家实验室估计，2019年)，例如由英国华威大学的Hatef Sadeghi编辑和审查的技术
{"title":"Thermoelectric Materials: Current Status and Future Challenges","authors":"Peter A. Finn, Ceyla Asker, K. Wan, E. Bilotti, O. Fenwick, C. Nielsen","doi":"10.3389/femat.2021.677845","DOIUrl":"https://doi.org/10.3389/femat.2021.677845","url":null,"abstract":"Net zero refers to the balance of the amount of greenhouse gas emissions produced and the amount removed from the atmosphere, and many companies and states have committed themselves to net zero targets. In June 2019, the United Kingdom became the first major economy in the world to pass a net zero emissions law. This ambitious target aims to reduce the UK’s net emissions of greenhouse gases by 100 per cent relative to 1,990 levels by 2,050 and replaces the UK’s previous target to reduce emissions by at least 80%. Sweden, France, Denmark, New Zealand and Hungary have also now succeeded in putting net zero targets into law (Net Zero Emissions Race, 2020). Progress towards these net zero goals has so far been slow. For example, the United Kingdom is behind on even the original 80% target, and achieving the current aim by 2,050 will be challenging. One thing that is clear to the scientific community is that improvements in technology between now and 2,050 will be key to bring the net zero target within reach. However, this will only happen if we can identify technologies for accelerated development and invest in them now, so we can deliver benefits before the 2,050 deadline. There are multiple areas where new technologies can assist in energy generation and storage, including photovoltaics, wind and water turbines, the hydrogen economy, caloric materials and batteries, as well as energy saving technologies such as low loss electronics. Thermoelectric energy conversion materials were identified by the Henry Royce Institute and the Institute of Physics as a key area of materials research for achieving net zero emissions in the Materials for the Energy Transition (2019) report. Space heating and cooling (e.g., central heating or air conditioning), is one of the main contributors to emissions and accounts for around 17% of the UK’s CO2 emissions (Department for Business, Energy and industrial Strategy, 2018). In Saudi Arabia, one of the hottest and driest countries in the world, more than 70% of the kingdom’s electricity produced per year is consumed purely for air conditioning and cooling purposes, with the demand doubling during the summer (Demirbas et al., 2017). This home water and space heating is typically achieved through burning natural gas in countries with access to natural gas, and through electrically-powered airsource heat pumps elsewhere. More widespread deployment of air-source heat pumps creates increased electricity demand, so solar-integrated heat pumps are also being investigated as another potential alternative to meet current space heating and domestic hot water demands with a reduced draw from the grid. However, these pumps use refrigerants such as HFCs, which are powerful greenhouse gases, so heat pumps that use other types of materials, such as thermoelectric and caloric materials need to be investigated as “greener” options. Thermoelectric materials use temperature differences to generate electrical energy. They can therefore pro","PeriodicalId":119676,"journal":{"name":"Frontiers in Electronic Materials","volume":"208 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114254048","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 : 2020-06-04DOI: 10.3389/femat.2022.837651
A. Grockowiak, M. Ahart, T. Helm, G. Garbarino, K. Glazyrin, W. Coniglio, Ravhi S Kumar, M. Somayazulu, Y. Meng, Morgan Oliff, V. Williams, N. Ashcroft, R. Hemley, S. Tozer
The search for room temperature superconductivity has accelerated in the last few years driven by experimentally accessible theoretical predictions that indicated alloying dense hydrogen with other elements could produce conventional superconductivity at high temperatures and pressures. These predictions helped inform the synthesis of simple binary hydrides that culminated in the discovery of the superhydride LaH10 with a superconducting transition temperature T c of 260 K at 180 GPa. We have now successfully synthesized a metallic La-based superhydride with an initial T c of 294 K. When subjected to subsequent thermal excursions that promoted a chemical reaction to a higher order system, the T c onset was driven irreversibly to 556 K. X-ray characterization confirmed the formation of a distorted LaH10 based backbone that suggests the formation of ternary or quaternary compounds with substitution at the La and/or H sites. The results provide evidence for hot superconductivity, aligning with recent predictions for higher order hydrides under pressure.
{"title":"Hot Hydride Superconductivity Above 550 K","authors":"A. Grockowiak, M. Ahart, T. Helm, G. Garbarino, K. Glazyrin, W. Coniglio, Ravhi S Kumar, M. Somayazulu, Y. Meng, Morgan Oliff, V. Williams, N. Ashcroft, R. Hemley, S. Tozer","doi":"10.3389/femat.2022.837651","DOIUrl":"https://doi.org/10.3389/femat.2022.837651","url":null,"abstract":"The search for room temperature superconductivity has accelerated in the last few years driven by experimentally accessible theoretical predictions that indicated alloying dense hydrogen with other elements could produce conventional superconductivity at high temperatures and pressures. These predictions helped inform the synthesis of simple binary hydrides that culminated in the discovery of the superhydride LaH10 with a superconducting transition temperature T c of 260 K at 180 GPa. We have now successfully synthesized a metallic La-based superhydride with an initial T c of 294 K. When subjected to subsequent thermal excursions that promoted a chemical reaction to a higher order system, the T c onset was driven irreversibly to 556 K. X-ray characterization confirmed the formation of a distorted LaH10 based backbone that suggests the formation of ternary or quaternary compounds with substitution at the La and/or H sites. The results provide evidence for hot superconductivity, aligning with recent predictions for higher order hydrides under pressure.","PeriodicalId":119676,"journal":{"name":"Frontiers in Electronic Materials","volume":"188 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115506533","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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