Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA.
Science. 2014 May 9;344(6184):612-6. doi: 10.1126/science.1248783.
The existence of electronic symmetry breaking in the underdoped cuprates and its disappearance with increased hole density p are now widely reported. However, the relation between this transition and the momentum-space (k-space) electronic structure underpinning the superconductivity has not yet been established. Here, we visualize the Q = 0 (intra-unit-cell) and Q ≠ 0 (density-wave) broken-symmetry states, simultaneously with the coherent k-space topology, for Bi₂Sr₂CaCu₂O(8+δ) samples spanning the phase diagram 0.06 ≤ p ≤ 0.23. We show that the electronic symmetry-breaking tendencies weaken with increasing p and disappear close to a critical doping p(c) = 0.19. Concomitantly, the coherent k-space topology undergoes an abrupt transition, from arcs to closed contours, at the same p(c). These data reveal that the k-space topology transformation in cuprates is linked intimately with the disappearance of the electronic symmetry breaking at a concealed critical point.
在欠掺杂铜酸盐中存在电子对称破缺，并且随着空穴密度 p 的增加而消失，这一现象现在已经得到了广泛的报道。然而，这种转变与超导性所依赖的动量空间（k 空间）电子结构之间的关系尚未建立。在这里，我们可视化了 Q = 0（单元内）和 Q ≠ 0（密度波）破对称态，以及相干 k 空间拓扑，对于跨越相图 0.06 ≤ p ≤ 0.23 的 Bi₂Sr₂CaCu₂O(8+δ) 样品。我们表明，电子对称破缺的趋势随着 p 的增加而减弱，并在接近临界掺杂 p(c) = 0.19 时消失。同时，相干 k 空间拓扑在相同的 p(c) 处发生了突然的转变，从弧变为封闭的轮廓。这些数据表明，铜酸盐中 k 空间拓扑的转变与电子对称破缺在隐蔽临界点处的消失密切相关。
