Lattice Instability in High-Temperature Superconductors

高温超导体中的晶格不稳定性

• 批准号: 08044090
• 负责人: FUJITA Toshizo
• 金额: $ 3.33万
• 依托单位: HIROSHIMA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for international Scientific Research
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 无数据
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08044090/
• 关键词: high-temperature superconductors; single crystal; lattice instability; neutron scottering; de Haas van Alphen effect; Fermi surface; ドハース・ファン・アルフェン効果

In the vicinity of the doping level and the temperature range where the high-temperature superconductivity appcars, materials often encounter the lattice instability. From our acoustic study, the lattice instability and supercondueting transition are suggested to compete with each other in La_<2-x>Sr_xCuO_4 (LSCO). The aim of this research project is to inverstigatethe relation between the lattice instability and the superconductivity in LSCO and the reference material Sr_2RuO_4 (SRO). In collaboratin with a French group at Saclay, we (Japanese group) performed neutron experiments on our single-crystalline samples of LSCO and SRO.For SRO,we collaborated also with a British group at Cambridge on the deHaas van Alphen (dHvA) experiments to map the Fermi surface of SRO.Our works can be summarized as follows.1.We grew high-quality single crystals of LSCO,Nd-doped LSCO (LNSOC) and SRO.Part of the crystals were used for the X-ray diffraction, ultrasonic experiments, specific heat measurement … More s, dilatometry and measurements of transport coefficients. Another part of the crystals were sent to Saclay for the neutron experiments and some SRO crystals were used at Cambridge for the dHvA experiments.2.We obtained an evidence suggesting the stripe structure in LNSCO similar to what has been reported by Tranquada et al.But we should be careful enough to wait for our definite conclusion until we know the influence of lattice imperfection on the structure. We succeeded in analyzing the lattice structure of SRO in detail, the result of which has been published in Physica C.3.We could determine the Fermi surface for SRO from the dHvA experiment, which allowed us to discuss quantitatively the transport properties as well as the electronic speific heat. The result and discussion are published in four pieces of our recent papers.4.We also obtained various new findings on the nonmetallic out-of-plane conduction, the splitting of the density of states near the Fermi level due to the 1/8 anomaly in LNBCO as well as on the possible p-wave pairing in SRO. Less

在掺杂能级和高温超导电性所在的温度范围附近，材料经常会遇到晶格不稳定性。声学研究表明，La_xCuO_4(LSCO)中的晶格不稳定性和超导转变是相互竞争的。本研究的目的是反转LSCO的晶格不稳定性与超导电性之间的关系，以及参考物质Sr_2RuO_4(SRO)。在Saclay与法国团队的合作下，我们(日本团队)在我们的LSCO和SRO单晶样品上进行了中子实验。对于SRO，我们还与剑桥的一个英国团队合作进行了DeHaas van Alphen(DHvA)实验，以绘制SRO的费米面。我们的工作总结如下：1.我们生长了高质量的LSCO、掺Nd LSCO和SRO单晶，部分晶体用于X射线衍射、超声实验、比热测量…更多的是S、膨胀法和输运系数的测量。另一部分晶体被送到Saclay进行中子实验，一些SRO晶体在剑桥用于dHvA实验。2.我们得到的证据表明，LNSCO中的条纹结构与Tranquada等人报道的相似。但我们应该足够谨慎地等待我们的确定结论，直到我们知道晶格缺陷对结构的影响。我们成功地详细分析了SRO的晶格结构，其结果已经发表在Physica C.3上。我们可以从dHvA实验中确定SRO的费米面，这使得我们能够定量地讨论SRO的输运性质以及电子比热。结果和讨论发表在我们最近的四篇论文中。4.我们还在非金属平面外导电、由于LNBCO的1/8反常引起的费米能级附近的态密度分裂以及SRO中可能的p波配对方面获得了各种新的发现。较少

项目成果

N.E.Hussey. et al.: "The Normal State Magnetoresistance of Sr_2RuO_4" Phys.Rev.B.(in press).

N.E.赫西。

S.Sakita, T.Suzuki, F.Nakamura, M.Nohara, Y.Maeno, and T.Fujita: "Elastic Softening in Single-Crystalline La_<2-x>Sr_xCuO_4 around x=1/8" Physica B. 219 & 220. 216-218 (1996)

S.Sakita、T.Suzuki、F.Nakamura、M.Nohara、Y.Maeno 和 T.Fujita：“x=1/8 附近单晶 La_<2-x>Sr_xCuO_4 的弹性软化”Physica B. 219

X.Bao, Y.Maeno, Y.Tanaka, J.Nyhus and T.Fujita: "Changes in the Transport Properties and the Suppression of Superconductivity in La_<2-x-y>Nd_yBa_xCuO_4 at x=1/8" Advances in Superconductivity. VIII. 235-238 (1996)

X.Bao、Y.Maeno、Y.Tanaka、J.Nyhus 和 T.Fujita：“La_<2-x-y>Nd_yBa_xCuO_4 在 x=1/8 时输运特性的变化和超导性的抑制”超导性进展。

S.Sakita et al.: "Elastic Softening in Single-Crystalline La_<2-x>Sr_xCuO_4 around x=1/8" Physica B. 219-220. 216-218 (1996)

S.Sakita等人：“单晶La_2-x>Sr_xCuO_4在x=1/8附近的弹性软化”Physica B.219-220。

K.Ito,et al.: "Low-Temperature Structural Transitions and Tc-suppression in La_<2-x-y>Ba_xNd_yCuO_4" Advances in Superconductivity. VIII. 239-240 (1996)

K.Ito 等人：“La_<2-x-y>Ba_xNd_yCuO_4 中的低温结构转变和 Tc 抑制”超导进展。