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arXiv 1508.02429cond-mat.supr-con
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超导La $_{1.93}$ Sr $_{0.07}$ CuO $_4$中自旋有序和条纹钉扎的中子散射研究

Neutron scattering study of spin ordering and stripe pinning in superconducting La$_{1.93}$Sr$_{0.07}$CuO$_4$

H. Jacobsen, I. A. Zaliznyak, A. T. Savici, B. L. Winn, S. Chang, M. Huecker, G. D. Gu, J. M. Tranquada

摘要:

在欠掺杂铜氧化物中,电荷有序、自旋涨落和超导电性之间的关系仍然存在争议。我们用中子散射技术研究了转变温度为$T_c = 20$~K的超导体LaPDMATHABMM SrPDMATHABMN CuO $_4$中的这些现象。在$T\ll T_c$,我们发现无公度自旋波动与准弹性能谱和没有迹象的间隙内的能量范围从0.2至15毫电子伏。一个弱的弹性磁分量的增长低于$\sim10$~K,从本地探针的结果一致。关于原子晶格,我们已经发现了意外的强烈波动的CuO $_6$八面体的Cu-O键,这是与不等价的O网站内的CuO $_2$平面。此外,我们观察到一个弱的弹性$(3\bar{3}0)$超晶格峰,这意味着减少晶格对称性。不等价的O位点的存在合理化的各种证据,在欠掺杂\lsco的电荷条纹秩序。超导性与准静态自旋条纹有序的共存表明存在交织的秩序;然而,条纹取向远离Cu-O键的旋转可能与超导能隙函数的节点处的有限能隙的证据有关。

英文摘要:

The relationships among charge order, spin fluctuations, and superconductivity in underdoped cuprates remain controversial. We use neutron scattering techniques to study these phenomena in La$_{1.93}$Sr$_{0.07}$CuO$_4$, a superconductor with a transition temperature of $T_c = 20$~K. At $T\ll T_c$, we find incommensurate spin fluctuations with a quasielastic energy spectrum and no sign of a gap within the energy range from 0.2 to 15 meV. A weak elastic magnetic component grows below $\sim10$~K, consistent with results from local probes. Regarding the atomic lattice, we have discovered unexpectedly strong fluctuations of the CuO$_6$ octahedra about Cu-O bonds, which are associated with inequivalent O sites within the CuO$_2$ planes. Furthermore, we observed a weak elastic $(3\bar{3}0)$ superlattice peak that implies a reduced lattice symmetry. The presence of inequivalent O sites rationalizes various pieces of evidence for charge stripe order in underdoped \lsco. The coexistence of superconductivity with quasi-static spin-stripe order suggests the presence of intertwined orders; however, the rotation of the stripe orientation away from the Cu-O bonds might be connected with evidence for a finite gap at the nodal points of the superconducting gap function.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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