Fermiology of High Temperature Superconductors

高温超导体的费米学

• 批准号: EP/F038836/1
• 负责人: Antony Carrington
• 金额: $ 70.01万
• 依托单位: University of Bristol
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2008
• 资助国家: 英国
• 起止时间: 2008 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FF038836%2F1
• 关键词: Fermiology; Temperature; Superconductors

Despite having been discovered more than twenty years ago, the unusual properties of high temperature cuprate superconductors (HTSC) are still far from being well understood. The most important question is of course, why is the superconducting transition temperature so high and how might it be raised even further? A strongly linked question to this is, what is the nature of the normal (non-superconducting) state of these materials and how does this evolve as the number density of conduction electrons is varied by chemical doping? Clearly, a complete understanding of the former requires knowledge of the latter. Until recently our main experimental probes of the normal state were macroscopic transport measurements (electrical resistivity, Hall effect etc.) and angle resolved photoemission spectroscopy (ARPES). The recent discovery that quantum oscillations can also be observed in some cuprate superconductors at very high magnetic field (> 40 Tesla) has made a very big impact on the subject. Most importantly, it reveals that the true nature of the Fermi surface of the slightly doped cuprates is significantly different to that suggested previously by ARPES measurements. The main features of the quantum oscillation technique are first that the measurements probe the electronic structure right at the Fermi level with much higher energy and momentum resolution than ARPES, and second that they probe the bulk of the sample and so are not influenced by surface defects or reconstructions. A second related technique for investigating the Fermi surface is angle dependent magnetoresistance (ADMR). This has recently proven a very successful technique particularly for investigating more heavily doped HTSC and has revealed in great detail the full three-dimensional Fermi surface topology on one particular cuprate family. Such three-dimensional information is currently inaccessible to ARPES. ADMR has an additional advantage over conventional quantum oscillation techniques in that it can also reveal the temperature and momentum dependence of the transport scattering rate, a key parameter that largely determines the evolution of the anomalous transport properties of HTSC across the phase diagram.Both the quantum oscillations and ADMR have now become powerful techniques in the study of HTSC because of the recent development of facilities which are able to produce very high magnetic fields (up to 100 Tesla) and recent improvements in the signal-to-noise ratios at these facilities. The goal of this proposal is to make best use of these timely developments and to study quantum oscillations and ADMR in a variety of different HTSC materials at very high magnetic fields. In so doing we aim to gain a deeper understanding of how the normal state electronic structure of high temperature cuprate superconductors evolves as a function of the electron density. We will also attempt to couple our Fermi surface studies to measurements of their resistivity and Hall effect in the limiting low temperature (high magnetic field) regime.

尽管高温铜氧化物超导体（HTSC）早在二十多年前就被发现了，但其不同寻常的性质仍然远未得到很好的理解。当然，最重要的问题是，为什么超导转变温度如此之高，以及如何进一步提高它？一个与此密切相关的问题是，这些材料的正常（非超导）状态的性质是什么，以及当传导电子的数量密度通过化学掺杂而变化时，这种状态是如何演变的？显然，对前者的全面理解需要对后者的了解。直到最近，我们对正常态的主要实验探针是宏观输运测量（电阻率，霍尔效应等）。和角分辨光电子能谱（ARPES）。最近发现在某些铜氧化物超导体中，在很高的磁场（> 40特斯拉）下也可以观察到量子振荡，这对这一课题产生了很大的影响。最重要的是，它揭示了轻微掺杂的铜氧化物的费米面的真实性质是显着不同的，以前建议的ARPES测量。量子振荡技术的主要特点是，首先，测量探测电子结构的权利，在费米能级具有更高的能量和动量分辨率比ARPES，第二，他们探测样品的大部分，因此不受表面缺陷或重建。研究费米面的第二种相关技术是角度相关磁阻（ADMR）。这最近已被证明是一个非常成功的技术，特别是用于调查更重掺杂的高温超导，并详细揭示了一个特定的铜酸盐家族的完整的三维费米表面拓扑结构。这种三维信息目前还无法进入ARPES。ADMR相对于传统的量子振荡技术具有额外的优点，因为它还可以揭示输运散射速率的温度和动量依赖性，量子振荡是一个关键参数，它在很大程度上决定了高温超导的反常输运性质在相图上的演化。由于最近发展了能够产生非常高的磁场（高达100特斯拉）和最近的改善，在这些设施的信噪比。该提案的目标是充分利用这些及时的发展，并研究量子振荡和ADMR在各种不同的高温超导材料在非常高的磁场。在这样做的过程中，我们的目标是获得一个更深入的了解如何正常状态的高温铜氧化物超导体的电子结构演变的电子密度的函数。我们还将尝试耦合我们的费米表面的研究，以测量其电阻率和霍尔效应在极限低温（高磁场）制度。

项目成果

Quantum oscillations in the parent pnictide BaFe 2 As 2 : Itinerant electrons in the reconstructed state

• DOI: 10.1103/physrevb.80.064507
• 发表时间: 2009-02
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: J. Analytis;J. Analytis;R. McDonald;J. Chu;J. Chu;S. Riggs;A. Bangura;C. Kucharczyk;C. Kucharczyk;M. Johannes;I. Fisher;I. Fisher

Quantum oscillation studies of the Fermi surface of LaFePO

• DOI: 10.1016/j.physc.2009.03.045
• 发表时间: 2009-01
• 期刊: Physica C-superconductivity and Its Applications
• 影响因子: 1.7
• 作者: A. Carrington;A. Coldea;J. Fletcher;N. Hussey;C. Andrew;A. Bangura;J. Analytis;J. Chu;A. S. Erickson;I. Fisher;R. McDonald

Quantum oscillations in the parent pnictide BaFe$_2$As$_2$ : itinerant electrons in the reconstructed state

母体磷元素 BaFe$_2$As$_2$ 中的量子振荡：处于重建状态的流动电子

• DOI: 10.48550/arxiv.0902.1172
• 发表时间: 2009
• 作者: Analytis J

Topological change of the Fermi surface in ternary iron pnictides with reduced c/a ratio: a de Haas-van Alphen study of CaFe2P2.

• DOI: 10.1103/physrevlett.103.026404
• 发表时间: 2009-05
• 期刊: Physical review letters
• 影响因子: 8.6
• 作者: A. Coldea;C. Andrew;J. Analytis;J. Analytis;Ross McDonald;A. Bangura;Jiun-Haw Chu;Jiun-Haw Chu;I. Fisher;I. Fisher;Antony Carrington