arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0801.0087cond-mat.supr-con
收藏

超导体Bi_{2} Sr_{2} O_{8+δ}中空穴密度强衰减时电子激发谱的演化

Evolution of the electronic excitation spectrum with strongly diminishing hole-density in superconducting Bi_{2}Sr_{2}CaCu_{2}O_{8+δ}

J. W. Alldredge, Jinho Lee, K. McElroy, M. Wang, K. Fujita, Y. Kohsaka, C. Taylor, H. Eisaki, S. Uchida, P. J. Hirschfeld, J. C. Davis

发表信息：
Nature Physics, 4 319-326 (2008)
阅读 PDF
arXiv 页面 ↗HTML 原文 ↗

摘要：

对它的激发光谱的完整了解将极大地有助于理解在轻空穴掺杂的铜氧化物中发生的不寻常的超导形式。本文用隧道谱法测量了超导体Bi_{2} Sr_{2} CaCu_{2} O_{8+/delta}在宽空穴密度p范围内的电子激发态N（E）的T \to 0谱。我们引入了一个基于各向异性能隙/Delta（\vec k）=/ Delta_{1}（Cos（k_{x}）-Cos（k_{y}））/2加上随能量线性变化的有效散射率/ Gamma_{2}（E）的N（E）参数化。我们证明，这种形式的N（E）允许成功拟合的差分隧道电导谱在整个大部分的Bi_{2} Sr_{2} CaCu_{2} O_{8+/delta}相图。所得到的平均f Delta_{1}值随着p沿着激发到“赝能隙”能量的熟悉轨迹的下降而上升，而关键散射率f Gamma_{2} ^{*}= f Gamma_{2}（E=/ Delta_{1}）随着系统从p~16%欠掺杂到p<10%而从低于~ 1 meV增加到接近25 meV的值。因此，一个单一的，粒子-空穴对称的，各向异性的能隙，结合强烈的能量和掺杂相关的有效散射率，可以描述的光谱，而不求助于另一个有序的状态。然而，我们也观察到两个不同的和发散的能量尺度的系统：能隙最大值/ Delta_{1}和较低的能量尺度/ Delta_{0}分离的空间均匀和异质的电子结构。

英文摘要：

A complete knowledge of its excitation spectrum could greatly benefit efforts to understand the unusual form of superconductivity occurring in the lightly hole-doped copper-oxides. Here we use tunnelling spectroscopy to measure the T\to 0 spectrum of electronic excitations N(E) over a wide range of hole-density p in superconducting Bi_{2}Sr_{2}CaCu_{2}O_{8+/delta}. We introduce a parameterization for N(E) based upon an anisotropic energy-gap /Delta (\vec k)=/Delta_{1}(Cos(k_{x})-Cos(k_{y}))/2 plus an effective scattering rate which varies linearly with energy /Gamma_{2}(E) . We demonstrate that this form of N(E) allows successful fitting of differential tunnelling conductance spectra throughout much of the Bi_{2}Sr_{2}CaCu_{2}O_{8+/delta} phase diagram. The resulting average /Delta_{1} values rise with falling p along the familiar trajectory of excitations to the 'pseudogap' energy, while the key scattering rate /Gamma_{2}^{*}=/Gamma_{2}(E=/Delta_{1}) increases from below ~1meV to a value approaching 25meV as the system is underdoped from p~16% to p<10%. Thus, a single, particle-hole symmetric, anisotropic energy-gap, in combination with a strongly energy and doping dependent effective scattering rate, can describe the spectra without recourse to another ordered state. Nevertheless we also observe two distinct and diverging energy scales in the system: the energy-gap maximum /Delta_{1} and a lower energy scale /Delta_{0} separating the spatially homogeneous and heterogeneous electronic structures.

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。

↑