The onset temperature of superconducting fluctuation Tonset of Bi2Sr2-xRxCuOy (R=La and Eu) was studied by measuring the Nernst effect. We found that Tonset has a x and R dependence that is quite different from both the pseudogap temperature T* and the critical temperature Tc. Our results support the picture that the incoherent superconductivity, which has been observed below Tonset, is qualitatively different from the pseudogap phenomenon that is characterized by T*. The experimentally obtained phase diagram indicates that the pseudogap state suppresses Tc and enhances superconducting fluctuation while having only small influence on Tonset.
Coexistence of the superconducting energy gap and pseudogap above and below the transition temperature of superconducting cuprates
我们表示的超导间隙，$Δ(T)$，在$s$和d波对称的热力学函数。应用到Bi $_2$ Sr $_2$ CaCu $_2$ O $_{8+δ}$和Y $_{0.8}$ Ca $_{0.2}$ Ba $_2$ Cu $_3$ O $_{7-δ}$，我们发现，对于所有的掺杂$Δ(T)$持续存在，作为一个部分的差距，高以上$T_c$由于强的超导涨落。因此，一般来说，在$T_c$上方存在两个能隙，超导能隙和赝能隙，有效地调和了关于赝能隙物理的两种高度极化的观点。
Paired Cluster Model of High-Tc Superconductivity:Explanation for Pseudogap Critical Concentration, Vortex Core Pseudogap and Possible Stripe Phase in High-Tc Superconductors
We compare the pole structure of the electronic Green's function obtained by Cluster Dynamical Mean Field Theory to the results from the fractionalized Pair Density Wave idea. In the superconducting phase, we can consider the system in a state with coexistence of Superconducting and Charge order. Writing the Green's function in a way analogous to the previously proposed "hidden-fermions" model from S. Sakai et al (2016) leads to a similar pole structure for the self-energy. The fractionalization of the Pair Density Wave order also describes the pseudogap phase as a superposition of superconduc…
Competition between the Pseudogap and Superconducting States of Bi$_{2}$Sr$_{2}$Ca$_{0.92}$Y$_{0.08}$Cu$_{2}$O$_{8+δ}$ Single Crystals Revealed by Ultrafast Broadband Optical Reflectivity
用超快宽带瞬态反射率实验研究了Bi $_{2}$ Sr $_{2}$ Ca $_{0.92}$ Y $_{0.08}$ Cu $_{2}$ O $_{8+δ}$中赝能隙的非平衡动力学与超导相的相互作用.一旦建立了超导电性，赝能隙的弛豫速度就会比正常状态快2倍，而相应的瞬态反射率变化在$\sim$ 0.5 ps后改变符号。$\sim$。结果可以用一组耦合的赝能隙和超导序参量的微分方程来描述。耦合项的符号和强度表明两相之间的竞争非常弱，允许它们共存。
We obtain the superfluid weight and Berezinskii-Kosterlitz-Thouless (BKT) transition temperature for highly unconventional superconducting states with the coexistence of chiral d-wave superconductivity, charge density waves and pair density waves in the strained graphene. Our results show that the strain-induced flat bands can promote the superconducting transition temperature approximately $50\%$ compared to that of the original doped graphene, which suggests that the flat-band superconductivity is a potential route to get superconductivity with higher critical temperatures. In particular, we…
The rate of quasiparticle recombination probes the onset of coherence in cuprate superconductors
电子超流在临界温度$T_c$从常规金属态凝聚的过程可以用BCS理论很好地描述。在低掺杂的铜氧化物中，高温超导性反而从非常规的金属“赝隙”相凝聚而成，该相表现出各种非费米液体性质。最近，已经清楚的是，电荷密度波（CDW）相存在于赝能隙区域内，出现在刚好高于$T_c$的温度$T_{CDW}$处。$T_c$和$T_{CDW}$的近似重合，以及CDW和低于$T_c$的超导有序的共存和竞争，表明它们密切相关。在这里，我们表明，这种非常规的前体的超流的冷凝反映在偏离BSC理论的预测准粒子的重组率。利用超快时间分辨反射率法研究了欠掺杂HgBa $_{2}$ CuO $_{4+δ}$（Hg-1201）和YBa $_{2}$ Cu $_{3}$ O $_{6+x}$（YBCO）单晶中准粒子复合寿命$τ_{qp}$随温度和磁场的变化.我们发现，$τ_{qp}(T)$表现出局部最大值在一个小的温度窗口附近的$T_c$，这是突出的在欠掺杂的样品与共存的电荷顺序和消失的应用程序的一个小的磁场。我们解释这种不寻常的，非BCS的行为，假定$T_c$标志着从相位波动SC/CDW复合顺序以上的SC/CDW冷凝物以下的过渡。我们的研究结果表明，在欠掺杂铜氧化物超流体是相干混合粒子-粒子和粒子-空穴对的凝聚。
