@article{9a81b65a677f4039ac95a1d7c98dffaf,
title = "Discovery of Lorentz-violating type II Weyl fermions in LaAlGe",
abstract = "In quantum field theory, Weyl fermions are relativistic particles that travel at the speed of light and strictly obey the celebrated Lorentz symmetry. Their low-energy condensed matter analogs are Weyl semimetals, which are conductors whose electronic excitations mimic the Weyl fermion equation of motion. Although the traditional (type I) emergent Weyl fermions observed in TaAs still approximately respect Lorentz symmetry, recently, the so-called type II Weyl semimetal has been proposed, where the emergent Weyl quasiparticles break the Lorentz symmetry so strongly that they cannot be smoothly connected to Lorentz symmetric Weyl particles. Despite some evidence of nontrivial surface states, the direct observation of the type II bulk Weyl fermions remains elusive. We present the direct observation of the type II Weyl fermions in crystalline solid lanthanum aluminum germanide (LaAlGe) based on our photoemission data alone, without reliance on band structure calculations. Moreover, our systematic data agree with the theoretical calculations, providing further support on our experimental results.",
author = "Xu, {Su Yang} and Nasser Alidoust and Guoqing Chang and Hong Lu and Bahadur Singh and Ilya Belopolski and Sanchez, {Daniel S.} and Xiao Zhang and Guang Bian and Hao Zheng and Husanu, {Marious Adrian} and Yi Bian and Huang, {Shin Ming} and Hsu, {Chuang Han} and Chang, {Tay Rong} and Jeng, {Horng Tay} and Arun Bansil and Titus Neupert and Strocov, {Vladimir N.} and Hsin Lin and Shuang Jia and Hasan, {M. Zahid}",
note = "Funding Information: We acknowledge J. D. Denlinger, S. K. Mo, A. V. Fedorov, M. Hashimoto, M. Hoesch, T. Kim, and V. N. Strocov for their beamline assistance at the ALS, the Stanford Synchrotron Radiation Lightsource, the Diamond Light Source, and the Swiss Light Source. We also thank D. Huse, I. Klebanov, A. Polyakov, P. Steinhardt, H. Verlinde, and A. Vishwanath for discussions. H. Lin acknowledges visiting scientist support from Princeton University. Funding: Work at Princeton University and Princeton-led synchrotron-based ARPES measurements were supported by the Gordon and Betty Moore Foundation EPiQS Initiative through (grant GBMF4547 to M.Z.H.). Single-crystal growth was supported by the National Basic Research Program of China (grant nos. 2013CB921901 and 2014CB239302), and characterization was supported by the U.S. Department of Energy (DE-FG-02-05ER46200). First-principles band structure calculations at the National University of Singapore were supported by the National Research Foundation (NRF), Prime Minister{\textquoteright}s Office, Singapore under its NRF fellowship (NRF award no. NRF-NRFF2013-03). The work at Northeastern Publisher Copyright: {\textcopyright} 2017 The Authors, some rights reserved.",
year = "2017",
month = jun,
doi = "10.1126/sciadv.1603266",
language = "English (US)",
volume = "3",
journal = "Science Advances",
issn = "2375-2548",
publisher = "American Association for the Advancement of Science",
number = "6",
}