Temperature-dependent pseudogap-like features in tunnel spectra of high-Tc cuprates as a manifestation of charge-density waves
Temperature-dependent pseudogap-like features in tunnel spectra of high-Tc cuprates as a manifestation of charge-density waves
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DOI：
10.1088/0953-8984/20/42/425218
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发表时间：
2008-09
期刊：
影响因子：
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通讯作者：
T. Ekino;A. Gabovich;Mai Suan Li;M. Pękała;H. Szymczak;A. I. Voitenko
中科院分区：
文献类型：
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作者：
T. Ekino;A. Gabovich;Mai Suan Li;M. Pękała;H. Szymczak;A. I. Voitenko
计算了正常金属与空间非均匀超导体之间或两个这样的超导体之间的隧道电导的温度T的变化。介电间隙被认为是由于电子-声子(对于Peierls绝缘体)或库仑(对于激子绝缘体)相互作用而产生的电荷密度波(CDW)的结果。在具有不同参数的CDW超导体(CDW)的随机区域上进行了空间平均。计算的隧道谱表明，在超导转变的实际临界温度附近或以上，具有明显的低温峰结构的非对称态的电子密度在较高T处的电子密度在接近或高于实际临界温度时发生了平滑的转变。由此可见，倾峰结构和伪成图都是同一现象的表现。文中还讨论了CDW引起的背景对G(V)贡献的不对称性。这些结果解释了Bi2Sr2CaCu2O8+δ和其他相关的高T_c铜酸盐的G(V)的特殊特征。
Temperature, T, variations of the tunnel conductance G(V) were calculated for junctions between a normal metal and a spatially inhomogeneous superconductor with a dielectric gap on the nested sections of the Fermi surface or between two such superconductors. The dielectric gapping was considered to be a consequence of the charge density wave (CDW) appearance due to the electron–phonon (for a Peierls insulator) or a Coulomb (for an excitonic insulator) interactions. Spatial averaging was carried out over random domains with varying parameters of the CDW superconductor (CDWS). The calculated tunnel spectra demonstrate a smooth transformation from asymmetric patterns with a pronounced dip–hump structure at low T into those with a pseudogap depletion of the electron densities of states at higher T in the vicinity or above the actual critical temperatures of the superconducting transition for any of the CDWS domains. Thus, it is demonstrated that both the dip-hump structure and pseudogapping are manifestations of the same phenomenon. A possible CDW-induced asymmetry of the background contribution to G(V) is also touched upon. The results explain the peculiar features of G(V) for Bi2Sr2CaCu2O8+δ and other related high-Tc cuprates.