Erdenemunkh Unurbat, Koopman Brian, Fu Ling, Chatterjee Kamalesh, Wise W D, Gu G D, Hudson E W, Boyer Michael C
Department of Physics, Clark University, Worcester, Massachusetts 01610, USA.
Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Phys Rev Lett. 2016 Dec 16;117(25):257003. doi: 10.1103/PhysRevLett.117.257003.
We use scanning tunneling microscopy (STM) to study magnetic Fe impurities intentionally doped into the high-temperature superconductor Bi_{2}Sr_{2}CaCu_{2}O_{8+δ}. Our spectroscopic measurements reveal that Fe impurities introduce low-lying resonances in the density of states at Ω_{1}≈4 meV and Ω_{2}≈15 meV, allowing us to determine that, despite having a large magnetic moment, potential scattering of quasiparticles by Fe impurities dominates magnetic scattering. In addition, using high-resolution spatial characterizations of the local density of states near and away from Fe impurities, we detail the spatial extent of impurity-affected regions as well as provide a local view of impurity-induced effects on the superconducting and pseudogap states. Our studies of Fe impurities, when combined with a reinterpretation of earlier STM work in the context of a two-gap scenario, allow us to present a unified view of the atomic-scale effects of elemental impurities on the pseudogap and superconducting states in hole-doped cuprates; this may help resolve a previously assumed dichotomy between the effects of magnetic and nonmagnetic impurities in these materials.
我们使用扫描隧道显微镜（STM）来研究有意掺杂到高温超导体Bi₂Sr₂CaCu₂O₈₊δ中的磁性铁杂质。我们的光谱测量表明，铁杂质在Ω₁≈4 meV和Ω₂≈15 meV的态密度中引入了低能共振，这使我们能够确定，尽管铁杂质具有较大的磁矩，但准粒子被铁杂质的势散射在磁散射中占主导地位。此外，通过对铁杂质附近和远离铁杂质处的局域态密度进行高分辨率空间表征，我们详细描述了杂质影响区域的空间范围，并提供了杂质对超导态和赝能隙态影响的局部视图。我们对铁杂质的研究，结合在双能隙情景下对早期STM工作的重新解释，使我们能够对元素杂质在空穴掺杂铜酸盐中对赝能隙和超导态的原子尺度效应提出一个统一的观点；这可能有助于解决此前认为的这些材料中磁性杂质和非磁性杂质效应之间的二分法问题。
