We study the timely issue of charge order checkerboard patterns observed in a variety of cuprate superconductors. We suggest a minimal model in which strong quantum fluctuations in the vicinity of a single antiferromagnetic quantum critical point generate the complexity seen in the phase diagram of cuprates superconductors and, in particular, the evidenced charge order. The Fermi surface is found to fractionalize into hotspots and antinodal regions, where physically different gaps are formed. In the phase diagram, this is reflected by three transition temperatures for the formation of pseudogap, charge density wave, and superconductivity (or quadrupole density wave if a sufficiently strong magnetic field is applied). The charge density wave is characterized by modulations along the bonds of the CuO lattice with wave vectors connecting points of the Fermi surface in the antinodal regions. These features, previously observed experimentally, are so far unique to the quantum critical point in two spatial dimensions and shed a new light on the interplay between strongly fluctuating critical modes and conduction electrons in high-temperature superconductors.
Strong Coupling Superconductivity in the Vicinity of the Structural Quantum Critical Point in (Ca$_x$Sr$_{1-x}$)$_3$Rh$_4$Sn$_{13}$
超导准方钴矿（Ca $_x$ Sr $_{1-x}$）$_3$ Rh $_4$ Sn $_{13}$族的结构量子临界点为$x_c=0.9$，超导转变温度$T_c$在该临界点附近有一个圆顶形的变化，我们用比热探测了整个系列跨越量子临界点的正常态和超导态.我们的分析表明，一个显着降低的有效德拜温度接近$x_c$，我们解释为伴随着结构不稳定性的声子软化的结果。此外，在结构量子临界点附近发现$2Δ/k_BT_c$和$ΔC/γT_c$的显著大的增强超过Bardeen-Cooper-Schrieffer（BCS）值。（Ca $_{x}$ Sr $_{1-x}$）$_3$ Rh $_4$ Sn $_{13}$的相图为研究结构量子临界性和强电子-声子耦合超导电性之间的相互作用提供了一个模型系统。
Soft phonon modes in the vicinity of the structural quantum critical point
准方钴矿超导体$A_3T_4$ Sn $_{13}$（$A$ =Sr，Ca; $T$ =Ir，Rh，Co）是高度可调谐的，其特征在于结构量子临界点。我们构建了这些等价化合物的温度-晶格常数相图，分别将Ca $_{3}$ Rh $_4$ Sn $_{13}$和Ca $_{3}$ Co $_4$ Sn $_{13}$作为接近和远离结构量子临界点的成员。解卷积的晶格比热和电阻率提供了一个近似的声子态密度$F(ω)$和电子-声子输运耦合函数$α_{tr}^2F(ω)$的钙$_{3}$铑$_4$锡$_{13}$和钙$_{3}$钴$_4$锡$_{13}$，使我们能够调查的结构量子临界点的影响。我们的结果支持声子软化的情况接近结构量子临界点，并解释了增强的耦合强度接近结构不稳定性。
Detection of an Unconventional Superconducting Phase in the Vicinity of the Strong First-Order Magnetic Transition in CrAs Using ^75As-Nuclear Quadrupole Resonance
Complex magnetism and non-Fermi liquid state in the vicinity of the quantum critical point in the CeCo$_{1-x}$Fe$_x$Ge$_3$ series
我们报告了对CeCo $_{1-x}$ Fe $_{x}$ Ge $_3$合金的广泛研究，通过掺杂顺磁性CeFeGe $_3$化合物，将CeCoGe $_3$中的反铁磁有序阻尼到0 K，从而显示出量子临界点（QCP）。QCP的存在是通过使用广泛的实验方法检测非费米液体行为（NFL）来确认的：磁化率，比热，电阻率，磁阻和热电功率。在热电功率的情况下，我们发现$x$的塞贝克系数在0.6左右，即在QCP附近有明显的增强。最后，不同的互补研究使得能够构建CeCo $_{1-x}$ Fe $_{x}$ Ge $_3$系统的复杂磁相图，包括Ce基态的晶体电场分裂所施加的能量标度。
Magnetism trends in doped Ce-Cu intermetallics in the vicinity of quantum criticality: realistic Kondo lattice models based on dynamical mean-field theory
本文用实际电子结构计算和动力学平均场论（DMFT）相结合的方法，描述了典型重费米子化合物CeCu中Au掺杂的$_6$的量子临界点（QCP），并计算了Ce的定域$4f$ -电子.比较了Ce（Cu $_{1-ε}$ Au $_ε$）$_6$与Co掺杂CeCu $_{5}$的磁性趋势，后者位于最早的稀土永磁化合物之一Ce（Co，Cu）$_5$的组成空间的非铁磁性一侧.构造了一个真实的Doniach相图，表明该体系在Ce（Cu $_{1-x}$ Co $_x$）$_5$的$0.2<x<0.4$中跨越了近藤晶格中的一个磁量子临界点.比较了Au掺杂CeCu $_6$和Co掺杂CeCu $_5$，发现后者在QCP附近的扫描区完全覆盖了前者。这些趋势的散装稀土永磁体的矫顽力的影响进行了讨论。
Possible quantum fluctuations in the vicinity of the quantum critical point of $\mathbf{(Sr, Ca)_3Ir_4Sn_{13}}$ revealed by high-energy X-ray diffraction study
Avoided ferromagnetic quantum critical point: Antiferromagnetic ground state in substituted CeFePO
用磁化率和比热测量方法研究了量子临界材料CeFePO附近的两个取代系列Ce（Ru $_{1-x}$ Fe $_{x}$）PO和CeFe（As $_{1-y}$ P $_{y}$）O单晶。我们观察到一个反铁磁基态的量子临界点附近，与显着的变磁性转变为$H\parallel c$，这是磁硬方向。我们的结果验证了取代CeFePO避免了铁磁量子临界点，因为我们清楚地表明，铁磁基态的变化，反铁磁的，当接近量子临界点。
Nonperturbative functional renormalization-group approach to transport in the vicinity of a $(2+1)$-dimensional O($N$)-symmetric quantum critical point
