Discovery of Ĉ$_2$ rotation anomaly in topological crystalline insulator SrPb

结晶HfTe5的手性反常和超高迁移率

The Chiral Anomaly and Ultrahigh Mobility in Crystalline HfTe5

HfTe 5被预测为研究拓扑相的一个有前途的平台。本文通过电输运研究，首次在HfTe_5晶体中观察到了手征反常和迁移率。当外加磁场与电场方向平行（B//E）时，HfTe_5的磁电阻率为负，当B偏离E方向时，磁电阻率迅速消失。定量拟合进一步证实了手征异常作为基础物理。此外，通过分析纵向和霍尔迹线的电导率张量，揭示了HfTe 5中的载流子迁移率和超低载流子密度，这为潜在的电子应用铺平了道路。

Topological Crystalline Insulators with $C_2$ Rotation Anomaly

Based on first-principles calculations and symmetry-based indicator analysis, we find a class of topological crystalline insulators (TCIs) with $C_2$ rotation anomaly in a family of Zintl compounds, including $\mathrm{Ba}_{3}\mathrm{Cd}_{2}\mathrm{As}_{4}$, $\mathrm{Ba}_{3}\mathrm{Zn}_{2}\mathrm{As}_{4}$ and $\mathrm{Ba}_{3}\mathrm{Cd}_{2}\mathrm{Sb}_{4}$. The nontrivial band topology protected by coexistence of $C_2$ rotation symmetry and time-reversal symmetry $T$ leads to two surface Dirac cones at generic momenta on both top and bottom surfaces perpendicular to the rotation axis. In additi…

Dirac和Weyl半金属中手征反常的光电子能谱可视化

Visualizing the chiral anomaly in Dirac and Weyl semimetals with photoemission spectroscopy

量子反常是量子涨落对经典对称性的破坏。它们决定了从基本粒子到晶体材料的不同性质的物理系统如何对外部扰动作出拓扑反应，而对局部细节不敏感。反常范例是由手征反常的发现引发的，手征反常有助于π介子衰变为光子，并影响$^3$ He-A中超流涡旋的运动。在固态下，它也从根本上影响拓扑Weyl和狄拉克半金属的性质，最近在TaAs，Na $_3$ Bi，Cd $_3$ As $_2$和ZrTe $_{5}$中实验实现。在这项工作中，我们提出的手征异常，不同的手征费米子之间的电荷密度不平衡的非正交电场和磁场诱导的最确定的后果，可以直接观察到这些材料与现有的技术的光电子能谱。与角度分辨率，手征异常被识别的特征注意到形状的图案的发射光谱，起源于不平衡的占领的体状态和以前未报道的动量依赖的能量转移的表面状态费米弧。我们进一步证明，手性异常同样留下的角度平均发射光谱的印记，方便其实验检测。因此，我们的工作提供了必要的理论输入，以促进凝聚态物质中的手征异常的直接可视化。

Graph theory-based structural analysis on density anomaly of silica glass

Analyzing the atomic structure of glassy materials is a tremendous challenge both experimentally and computationally, and the lack of direct, detailed insights into glass structure hinders our ability to navigate structure-property relationships. For instance, the structural origin of the density anomaly in silica glasses - the negative thermal expansion coefficient - is still poorly understood. Simulations based on molecular dynamics (MD) produce atomically resolved structures, but quantifying the role of disorder in the density anomaly is challenging. Here, we propose to use a a graph-theore…

铅硫族化合物的带隙反常和拓扑性质

Band gap anomaly and topological properties in lead chalcogenides

带隙异常是铅硫族化合物PbX（X=S，Se，Te，Po）中的一个众所周知的问题。结合量子化学从头算和紧束缚（TB）方法，研究了PbX的能带演化，发现PbTe的能带异常主要与Te 5s轨道的高能和Te 5s电子不规则扩展分布引起的s-p跳跃有关.此外，我们的计算表明，PbPo是一个间接的带隙（6.5 meV）半导体与带反转在L点，这清楚地表明，PbPo是一个拓扑晶体绝缘体（TCI）。计算得到的镜像陈数和表面态进一步证实了这一结论。

Probing charge pumping and relaxation of the chiral anomaly in a Dirac semimetal

The linear band crossings of 3D Dirac and Weyl semimetals are characterized by a charge chirality, the parallel or anti-parallel locking of electron spin to its momentum. Such materials are believed to exhibit a ${\bf E} \cdot {\bf B}$ chiral magnetic effect that is associated with the near conservation of chiral charge. Here, we use magneto-terahertz spectroscopy to study epitaxial Cd$_3$As$_2$ films and extract their conductivities $σ(ω)$ as a function of ${\bf E} \cdot {\bf B}$. As field is applied, we observe a remarkably sharp Drude response that rises out of the broader background. Its a…