Comment on “Anisotropic Scattering Caused by Apical Oxygen Vacancies in Thin Films of Overdoped High-Temperature Cuprate Superconductors”
Comment on “Anisotropic Scattering Caused by Apical Oxygen Vacancies in Thin Films of Overdoped High-Temperature Cuprate Superconductors”
复制标题
对“过掺杂高温铜酸盐超导体薄膜中顶端氧空位引起的各向异性散射”的评论
DOI：
10.1103/physrevlett.131.049701
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发表时间：
2023
影响因子：
8.6
通讯作者：
Hirschfeld, P. J.
中科院分区：
文献类型：
--
作者：
Özdemir, H. U.;Mishra, Vivek;Lee-Hone, N. R.;Kong, Xiangru;Berlijn, T.;Broun, D. M.;Hirschfeld, P. J.
见参考文件[1]Wang等人解决了过掺杂铜酸盐中的一个重要问题，迈出了理解这些材料中真实的缺陷结构的第一步，在这种情况下，顶点氧空位VO位于平面Cu的正上方。然而，所采取的方法存在一些问题，我们在本评论中对此进行了概述。潜在杂质。-的主要假设。[1]基于对称性的论点，是因为在顶氧pz轨道和它下面的Cu 3dx 2 − y2轨道之间没有跳跃，所以顶氧的主要耦合是到下一个最近的相邻Cu位点。这导致他们到一个实空间散射潜力的空缺，没有网站的条款，因此散射矩阵元素Vk，k 0强烈依赖于动量。然而，当从头计算进行，如在参考。[2]，La 2 − xSrxCuO 4（LSCO）中晶位中心顶端氧空位的杂质势实际上是由在晶位项控制的，以至于VO缺陷基本上充当了点散射体[见图1（a）]，其矩阵元素几乎与动量传递q无关。这种差异的原因是，通过使对称性的论点类似于跳跃过程，参考。[1]忽略了VO缺陷对紧邻其下方的Cu位点的能量的强静电贡献，因此错过了VO缺陷的重要各向同性贡献。然而，在LSCO中确实存在扩展的杂质电势的来源-以片晶为中心的Sr掺杂剂[图1（B）]-其引起强烈的动量依赖性Vk; k 0。请注意，在Ref。[1]散射率参数Γs和Γd被用来拟合实验，从而解决了文献[1]和[2]的主要定性差异。[1]和[2]没有出现在最终结果的水平上。费米面。过掺杂的LSCO经历了一个Lifshitz转变，在这个转变中，货车霍韦奇点穿过费米能级[3]。因此，费米面是远离各向同性，态密度和费米速度变化强烈的角度和掺杂，在参考文献中假设的圆形费米面。[1]的文件。这种各向异性对超流密度[4]和电导率[5]等物理性质有重要影响。费米面各向异性必须存在于杂质散射中，以产生强烈的角度依赖的散射率Γθ，这是参考文献[1]中的一个关键假设。[1]的文件。
In Ref.[1], Wang et al. address an important problem in the overdoped cuprates, taking the first steps toward understanding the structure of real defects in these materials, in this case the apical oxygen vacancy VO that sits immediately above the planar Cu. However, the approach taken has some issues, which we outline in this Comment. Impurity potentials.—The primary assumption of Ref.[1], based on symmetry arguments, is that since there is no hopping between the apical oxygen pz orbital and the Cu 3dx2− y2 orbital immediately below it, the leading couplings from the apical oxygen are to the nextnearest-neighboring Cu sites. This leads them to a realspace scattering potential for the vacancy that has no on-site term, and hence scattering matrix elements Vk; k0 that depend strongly on momentum. However, when ab initio calculations are carried out, as in Ref.[2], the impurity potential of the site-centered apical oxygen vacancy in La2− xSrxCuO4 (LSCO) is in fact dominated by the on-site term, to the point that the VO defect essentially acts as a point scatterer [see Fig. 1 (a)], with matrix elements that are almost independent of momentum transfer q. The reason for this discrepancy is that by making symmetry arguments analogous to those for hopping processes, Ref.[1] overlooks the strong electrostatic contribution the VO defect makes to the energy of the Cu site immediately below it, and is therefore missing the important isotropic contribution of the VO defects. Nevertheless, there does exist a source of extended impurity potentials in LSCO—the plaquette-centered Sr dopants [Fig. 1 (b)]—which give rise to strongly momentum-dependent Vk; k0. Note that in Ref.[1], scattering rate parameters Γs and Γd are used to fit to experiment, so the key qualitative differences between Refs.[1] and [2] do not appear at the level of final results.Fermi surface.—Overdoped LSCO undergoes a Lifshitz transition at which the van Hove singularity passes through the Fermi level [3]. As a result, the Fermi surface is far from isotropic, and the density of states and Fermi velocity vary strongly with angle and doping, in contrast to the circular Fermi surface assumed in Ref.[1]. This anisotropy has important consequences for physical properties such as superfluid density [4] and conductivity [5]. Fermi-surface anisotropy must be present for impurity scattering to produce a strongly angle-dependent scattering rate Γθ, a key assumption in Ref.[1].