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

基本信息

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

项目摘要

・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超导体模型的条纹顺序是一个合理的条纹模型，可以解释所谓的1/8问题，即，基于LA的铜层中对超导性的异常抑制，并且孔浓度为每CU P〜1/8。已经提出，从中子散射实验中观察到的在LA的铜岩中观察到的孔和旋转的静态顺序。如果条纹顺序是CUO_2平面的特征，则它不仅存在于LA基铜矿中，而且还存在于其他具有P〜1/8的高-TC蛋糕。在这项研究中，为了在基于BI的铜岩中搜索1/8异常，我们研究了BI_2SR_2CA__2CA_ <1-X> Y_X> Y_X（CU_ <1-Y> ZN_Y）_2O_2O_ <88+δ>单晶的超导过渡温度TC。 Zn替代是由于Zn固定的条纹图案的静态顺序。通过浮动区方法，我们成功地以0【或相等的] x（小于或等于] 0.5，y = 0，0.025）成功地生长了许多类型的单晶体，通过浮动区方法将其退火，以固定Ex ex…更多的cess氧含量σ。 TC的X依赖性定义为Meissner效应的开始温度，Y = 0，0.025在X〜0.35时似乎在X〜0.35处出现局部最小值。目前，正在测量霍尔效应和热电功率，以检查该局部最小值和1/8问题的相关性。低维量子旋转系统的助力电导率我们寻找了由于少量的κMagnon引起的较大的热导率，κMagnon在各种低维量子旋转系统中，例如两种量子<141 <141 <14 <141 <141 <141 <141。二维旋转二聚体系统SRCU_2（BO_3）_2，四腿旋转 - 旋转系统LA_2CU_2O_5，二维自旋系统CU_3B_2O_6和使用大型单个C的方法。在SR_ <14> Cu_ <24> O_ <41>的旋转隙状态下发现了大型κMagnon，其三重态兴奋的带宽度很大，这是由于镁的平均自由路径的增强。在无间隙系统中，已经发现，随着镁速度的增加而增加，这会随着Cu^<2+>旋转之间的交换增加而增加，并且在抗磁性自旋相关系统中比在铁磁自旋相关系统中更大。因此，得出的结论是，大型κMagnon的基本因素是自旋间隙系统中三重态兴奋的大带宽度，大型交换相互作用和抗磁性自旋相关，而不是铁磁自旋相关。较少的