@article {618,
	title = {Causal structure of interacting Weyl fermions in condensed matter systems},
	journal = {Nat. Commun.},
	volume = {14},
	year = {2023},
	pages = {2228},
	abstract = {The spacetime light cone is central to the definition of causality in the theory of relativity. Recently, links between relativistic and condensed matter physics have been uncovered, where relativistic particles can emerge as quasiparticles in the energy-momentum space of matter. Here, we unveil an energy-momentum analogue of the spacetime light cone by mapping time to energy, space to momentum, and the light cone to the Weyl cone. We show that two Weyl quasiparticles can only interact to open a global energy gap if they lie in each other{\textquoteright}s energy-momentum dispersion cones{\textendash}analogous to two events that can only have a causal connection if they lie in each other{\textquoteright}s light cones. Moreover, we demonstrate that the causality of surface chiral modes in quantum matter is entangled with the causality of bulk Weyl fermions. Furthermore, we identify a unique quantum horizon region and an associated {\textquoteright}thick horizon{\textquoteright} in the emergent causal structure.},
	doi = {10.1038/s41467-023-37931-w},
	url = {https://www.nature.com/articles/s41467-023-37931-w},
	author = {Wei-Chi Chiu and Guoqing Chang and Gennevieve M. Macam and Ilya Belopolski and Shin-Ming Huang and Robert Markiewicz and Jia-Xin Yin and Zi-Jia Cheng and Chi-Cheng Lee and Tay-Rong Chang and Feng-Chuan Chuang and Su-Yang Xu and Hsin Lin and M. Zahid Hasan and Arun Bansil}
}
@article {650,
	title = {Prediction of quantum spin Hall and Rashba effects in two-dimensional ilmenite oxides},
	journal = {Chinese J. Phys.},
	volume = {86},
	year = {2023},
	pages = {242},
	abstract = {Using first-principles calculations, we investigate the structural, electronic, and topological properties of two-dimensional (2D) pristine ilmenite oxides ABO$_{3}$ (A~=~Au, Ag, or Cu; and B~=~Bi, Sb, or As) and their corresponding Janus structures. Phonon dispersions reveal the dynamic stability of these compounds. Interestingly, pristine CuBiO$_{3}$ and AuBiO$_{3}$, and Janus Cu$_{0}$.$_{5}$Ag$_{0}$.$_{5}$BiO$_{3}$, Au$_{0}$.$_{5}$Cu$_{0}$.$_{5}$BiO$_{3}$, Au$_{0}$.$_{5}$Ag$_{0}$.$_{5}$BiO$_{3}$, and CuBi$_{0}$.$_{5}$As$_{0}$.$_{5}$O$_{3}$ are topological insulators, while AuBi$_{0}$.$_{5}$As$_{0}$.$_{5}$O$_{3}$, CuBi$_{0}$.$_{5}$Sb$_{0}$.$_{5}$O$_{3}$, and AuBi$_{0}$.$_{5}$Sb$_{0}$.$_{5}$O$_{3}$ are topological semimetals, as confirmed by their Z2 invariance and conducting edge states under the hybrid functional approach. Moreover, we found van Hove singularities in Au$_{0}$.$_{5}$Ag$_{0}$.$_{5}$BiO$_{3}$ and Cu$_{0}$.$_{5}$Ag$_{0}$.$_{5}$BiO$_{3}$ near the Fermi level, suggesting the coexistence of superconductivity and nontrivial topology. Finally, isotropic Rashba spin-splitting is studied in detail for Au$_{0}$.$_{5}$Ag$_{0}$.$_{5}$BiO$_{3}$. Our findings demonstrate that 2D ilmenite oxides can be a new material playground for potential spintronic applications.},
	doi = {10.1016/j.cjph.2023.09.022},
	url = {https://www.sciencedirect.com/science/article/abs/pii/S0577907323001806},
	author = {Susaiammal Arokiasamy and Gennevieve M. Macam and Rovi Angelo B. Villaos and Aniceto B. Maghirang and Zhi-Quan Huang and Chia-Hsiu Hsu and Guoqing Chang and Feng-Chuan Chuang}
}
@article {611,
	title = {Spin-orbit quantum impurity in a topological magnet},
	journal = {Nat. Commun.},
	volume = {11},
	year = {2020},
	pages = {4415},
	abstract = {Quantum states induced by single-atomic impurities are at the frontier of physics and material science. While such states have been reported in high-temperature superconductors and dilute magnetic semiconductors, they are unexplored in topological magnets which can feature spin-orbit tunability. Here we use spin-polarized scanning tunneling microscopy/spectroscopy (STM/S) to study the engineered quantum impurity in a topological magnet Co$_{3}$Sn$_{2}$S$_{2}$. We find that each substituted In impurity introduces a striking localized bound state. Our systematic magnetization-polarized probe reveals that this bound state is spin-down polarized, in lock with a negative orbital magnetization. Moreover, the magnetic bound states of neighboring impurities interact to form quantized orbitals, exhibiting an intriguing spin-orbit splitting, analogous to the splitting of the topological fermion line. Our work collectively demonstrates the strong spin-orbit effect of the single-atomic impurity at the quantum level, suggesting that a nonmagnetic impurity can introduce spin-orbit coupled magnetic resonance in topological magnets.},
	doi = {10.1038/s41467-020-18111-6},
	author = {Jia-Xin Yin and Nana Shumiya and Yuxiao Jiang and Huibin Zhou and Gennevieve M. Macam and Hano Omar Mohammad Sura and Songtian S. Zhang and Zi-Jia Cheng and Zurab Guguchia and Yangmu Li and Qi Wang and Maksim Litskevich and Ilya Belopolski and Xian P. Yang and Tyler A. Cochran and Guoqing Chang and Qi Zhang and Zhi-Quan Huang and Feng-Chuan Chuang and Hsin Lin and Hechang Lei and Brian M. Andersen and Ziqiang Wang and Shuang Ji and M. Zahid Hasan}
}
@article {598,
	title = {Quantum phase transition of correlated iron-based superconductivity in LiFe$_{1}$$_{-}$ₓCoₓAs},
	journal = {Phys. Rev. Lett.},
	volume = {123},
	year = {2019},
	pages = {217004},
	abstract = {The interplay between unconventional Cooper pairing and quantum states associated with atomic scale defects is a frontier of research with many open questions. So far, only a few of the high-temperature superconductors allow this intricate physics to be studied in a widely tunable way. We use scanning tunneling microscopy to image the electronic impact of Co atoms on the ground state of the LiFe$_{1}$$_{-}$ₓCoₓAs system. We observe that impurities progressively suppress the global superconducting gap and introduce low energy states near the gap edge, with the superconductivity remaining in the strong-coupling limit. Unexpectedly, the fully opened gap evolves into a nodal state before the Cooper pair coherence is fully destroyed. Our systematic theoretical analysis shows that these new observations can be quantitatively understood by the nonmagnetic Born-limit scattering effect in an s{\textpm}-wave superconductor, unveiling the driving force of the superconductor to metal quantum phase transition.},
	doi = {10.1103/PhysRevLett.123.217004},
	author = {Jia-Xin Yin and Songtian S. Zhang and Guangyang Dai and Yuanyuan Zhao and Andreas Kreisel and Gennevieve M. Macam and Xianxin Wu and Hu Miao and Zhi-Quan Huang and Johannes H. J. Martiny and Brian M. Andersen and Nana Shumiya and Daniel Multer and Maksim Litskevich and Zijia Cheng and Xian Yang and Tyler A. Cochran and Guoqing Chang and Ilya Belopolski and Lingyi Xing and Xiancheng Wang and Yi Gao and Feng-Chuan Chuang and Hsin Lin and Ziqiang Wang and Changqing Jin and Yunkyu Bang and M. Zahid Hasan}
}