The verification of the universality of the stripe order in single crystal of cuprate superconductors

铜酸盐超导体单晶条带序普适性验证

• 批准号: 13640346
• 负责人: NOJI Takashi
• 金额: $ 2.3万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13640346/
• 关键词: high temperature superconductor; stripe order; Bi-based cuprate; low-dimensional quantum spin system; thermal conductivity; 高温超伝導; 1; 8問題

・Stripe order of high-Tc superconductorThe stripe model is a plausible one which can explain the so-called 1/8 problem, namely, the anomalous suppression of superconductivity in the La-based cuprate with the hole concentration per Cu p 〜 1/8. It has been proposed that the static order of holes and spins observed in the La-based cuprate from the neutron scattering experiment. If the stripe order is characteristic of the CuO_2 plane, it will exist not only in the La-based cuprate but also other high-Tc cuprates with p 〜 1/8. In this study, in order to search for the 1/8 anomaly in the Bi-based cuprate, we investigated the superconducting transition temperature Tc of Bi_2Sr_2Ca_<1-x>Y_x(Cu_<1-y>Zn_y)_2O_<8+δ> single crystals. The Zn substitution is due to the stripe-patterned static order pinned by Zn. We have succeeded in growing of much kinds of single crystal with 0【less than or equal】x【less than or equal】0.5, y = 0, 0.025 by floating-zone method, which were annealed in order to fix ex … More cess oxygen content σ . The x dependence of Tc defined as the onset temperature of the Meissner effect has appeared a local minimum of Tc at x〜0.35 for y = 0, 0.025. At present, Hall effect and thermoelectric power are being measured in order to examine the correlation of this local minimum and 1/8 problem.Thermal conductivity of low-dimensional quantum spin systemWe have looked for large thermal-conductivity due to magnons, κmagnon in various kinds of low-dimensional quantum spin systems, such as the two-leg spin-ladder system Sr_<14>Cu_<24>O_<41>, the two-dimensional spin-dimer system SrCu_2(BO_3)_2, the four-leg spin-ladder system La_2Cu_2O_5, the two-dimensional spin system Cu_3B_2O_6 and the one-dimensional spin system Ca_2Y_2Cu_5O_<10>, using large-sized single-crystals grown by the TSFZ method. Large κmagnon has been found in the spin-gap state of Sr_<14>Cu_<24>O_<41> whose band width of the triplet excitation is large, owing to the enhancement of the mean free path of magnons. In gapless systems, it has been found that κmagnon increases with increasing magnon-velocity, which increases with increasing exchange-interaction between Cu^<2+> spins and is larger in antiferromagnetic spin-correlation systems than in ferrromagnetic spin-correlation systems. Therefore, it is concluded that essential factors of large κmagnon are a large band-width of the triplet excitation in a spin-gap system, a large exchange-interaction and antiferromagnetic spin-correlation rather than ferromagnetic spin-correlation. Less

·高tc超导体的条带顺序条带模型是一个合理的模型，可以解释所谓的1/8问题，即每Cu的空穴浓度为p ~ 1/8时，la基铜中超导性的异常抑制。通过中子散射实验，提出了在la基铜中观察到的空穴和自旋的静态顺序。如果条形顺序是CuO_2平面的特征，则条形顺序不仅存在于la基铜酸盐中，也存在于其他p ~ 1/8的高tc铜酸盐中。为了寻找bi基铜酸盐中的1/8异常，我们研究了Bi_2Sr_2Ca_<1-x>Y_x(Cu_<1-y>Zn_y)_2O_<8+δ>单晶的超导转变温度Tc。锌取代是由于锌固定的条形静态序。我们用浮区法成功地生长出了多种0≤x≤0.5,y = 0,0.025的单晶，并对其进行了退火处理，以固定氧含量σ。定义为迈斯纳效应起始温度的Tc的x依赖性在y = 0,0.025时在x ~ 0.35处出现了Tc的局部最小值。目前正在测量霍尔效应和热电功率，以检验这一局部最小值与1/8问题的相关性。我们在各种低维量子自旋系统中寻找由磁振子、κ磁振子引起的大热导率，如两足自旋阶梯系统Sr_<14>Cu_<24>O_<41>、二维自旋二聚体系统SrCu_2(BO_3)_2、四足自旋阶梯系统La_2Cu_2O_5、二维自旋系统Cu_3B_2O_6和一维自旋系统Ca_2Y_2Cu_5O_<10>等。采用TSFZ法生长的大尺寸单晶。在Sr_<14>Cu_<24>O_<41>的自旋间隙态中发现了大的κ磁振子，由于磁振子的平均自由程增强，其三重态激发的带宽较大。在无间隙系统中，发现κ磁振子随磁子速度的增加而增加，随Cu^<2+>自旋之间交换相互作用的增加而增加，并且在反铁磁自旋相关系统中比铁磁自旋相关系统更大。由此得出结论，大κ磁振子的关键因素是自旋间隙系统中大的三重态激发带宽度、大的交换相互作用和反铁磁自旋相关而不是铁磁自旋相关。少

项目成果

Kazutaka Kudo: "Anisotropic Magnetic Properties and Anomalous Thermal Conductivity in the bc Plane of the Quasi-Two-Dimensional Spin System Cu_3B_2O_6"Journal of the Physical Society of Japan. 72. 569-575 (2003)

工藤一隆：《准二维自旋系Cu_3B_2O_6的bc平面内的各向异性磁特性和反常热导率》日本物理学会学报。

Takashi Noji: "Single-crystal growth and anisotropy of the tetragonal 1-2-3 type superconductor Ca_<0.5>La_<1.25>Cu_3O_y"Journal of Low Temperature Physics. 131. 699-703 (2003)

Takashi Noji：“四方1-2-3型超导体Ca_<0.5>La_<1.25>Cu_3O_y的单晶生长和各向异性”低温物理杂志。

Yoji Koike: "Cu-Site-Substitution Effects on the 1/8 Anomaly in the High-Tc Cuprates and on the Anomaly at x=0.21 in La2-xSrxCuO4"Physica C. 357・360. 82-88 (2001)

小池洋司：“Cu位点取代对高温铜酸盐中1/8异常和La2-xSrxCuO4中x=0.21异常的影响”Physica C. 357・360 (2001)。

Kazutaka Kudo: "Antiferromagnetic Ordering in Single-Crystal Cu_3B_2O_6"Journal of the Physical Society of Japan. 70・4. 935-938 (2001)

工藤一隆：“单晶 Cu_3B_2O_6 中的反铁磁有序”，日本物理学会杂志 70・4（2001 年）。

Kazutaka Kudo: "Zn-Substitution Effects on the Thermal Conductivity of the Two-Dimensional Spin-Gap System SrCu_2(BO_3)_2 and the Two-Dimensional Antiferromagnetic System Cu_3B_2O_6 Single-Crystals"Physica B. 329-333. 910-911 (2003)

工藤一隆：“Zn取代对二维自旋间隙体系SrCu_2(BO_3)_2和二维反铁磁体系Cu_3B_2O_6单晶热导率的影响”Physica B. 329-333。