Doping dependence of the chemical potential and surface electronic structure in YBa2Cu3O6+x and La2-xSrxCuO4 using hard x-ray photoemission spectroscopy
Doping dependence of the chemical potential and surface electronic structure in YBa2Cu3O6+x and La2-xSrxCuO4 using hard x-ray photoemission spectroscopy
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DOI：
10.1103/physrevb.80.165132
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发表时间：
2009-10-01
影响因子：
3.7
通讯作者：
Golden, Mark S.
中科院分区：
文献类型：
--
作者：
Maiti, Kalobaran;Fink, Joerg;Golden, Mark S.
使用硬 X 射线光电子能谱研究了不同 x 值下 YBa2Cu3O6+x 和 La2-xSrxCuO4 的电子结构。实验结果表明，YBa2Cu3O6+x 化合物的裂解主要发生在 BaCuO3 配合物中，导致在较高 x 值时产生带电表面，在较低 x 值时产生不带电表面。核心级光谱的大部分成分表现出结合能随 x 变化的变化，由此可以得出化学势随 CuO2 层中空穴浓度变化的变化。在这两个系列的化合物中，从莫特-哈伯德绝缘体到类费米液体金属的过渡过程中化学势的掺杂依赖性非常不同。与文献中先前的研究一致，对于小孔浓度，La2-xSrxCuO4 中的化学势位移接近于零。在 YBa2Cu3O6+x 中，与迄今为止研究的所有其他掺杂铜酸盐类似，检测到低空穴掺杂时化学势的强烈变化。然而，小 x 时的反电荷磁化率结果显示不同掺杂铜酸盐之间存在很大差异。根据各种理论模型对结果进行了讨论。这些模型都不能令人满意。
The electronic structure of YBa2Cu3O6+x and La2-xSrxCuO4 for various values of x has been investigated using hard x-ray photoemission spectroscopy. The experimental results establish that the cleaving of YBa2Cu3O6+x compounds occurs predominantly in the BaCuO3 complex, leading to charged surfaces at higher x and to uncharged surfaces at lower x values. The bulk component of the core-level spectra exhibits a shift in binding energy as a function of x, from which a shift of the chemical potential as a function of hole concentration in the CuO2 layers could be derived. The doping dependence of the chemical potential across the transition from a Mott-Hubbard insulator to a Fermi-liquid-like metal is very different in these two series of compounds. In agreement with previous studies in the literature the chemical-potential shift in La2-xSrxCuO4 is close to zero for small hole concentrations. In YBa2Cu3O6+x, similar to all other doped cuprates studied so far, a strong shift of the chemical potential at low hole doping is detected. However, the results for the inverse charge susceptibility at small x shows a large variation between different doped cuprates. The results are discussed in view of various theoretical models. None of these models turns out to be satisfactory.