Mail Stop E536, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
Cavendish Laboratory, Cambridge University, Cambridge CB3 OHE, UK.
Science. 2015 Apr 17;348(6232):317-20. doi: 10.1126/science.aaa4990. Epub 2015 Mar 26.
In the quest for superconductors with higher transition temperatures (T(c)), one emerging motif is that electronic interactions favorable for superconductivity can be enhanced by fluctuations of a broken-symmetry phase. Recent experiments have suggested the existence of the requisite broken-symmetry phase in the high-T(c) cuprates, but the impact of such a phase on the ground-state electronic interactions has remained unclear. We used magnetic fields exceeding 90 tesla to access the underlying metallic state of the cuprate YBa2Cu3O(6+δ) over a wide range of doping, and observed magnetic quantum oscillations that reveal a strong enhancement of the quasiparticle effective mass toward optimal doping. This mass enhancement results from increasing electronic interactions approaching optimal doping, and suggests a quantum critical point at a hole doping of p(crit) ≈ 0.18.
在寻求具有更高转变温度（T(c)）的超导体的过程中，一个新兴的主题是，有利于超导性的电子相互作用可以通过对称破缺相的涨落来增强。最近的实验表明，高温超导铜酸盐中存在所需的对称破缺相，但这种相对基态电子相互作用的影响尚不清楚。我们使用超过 90 特斯拉的磁场来探测铜酸盐 YBa2Cu3O(6+δ)在广泛掺杂范围内的基础金属态，并观察到磁量子振荡，这表明在最佳掺杂时准粒子有效质量得到了强烈增强。这种质量增强是由于接近最佳掺杂时电子相互作用的增加，这表明在空穴掺杂 p(crit)≈0.18 处存在一个量子临界点。
