Observation of Fermi arcs and Weyl nodes in a noncentrosymmetric magnetic Weyl semimetal

Weyl semimetal (WSM), a novel state of quantum matter, hosts Weyl fermions as emergent quasiparticles resulting from the breaking of either inversion or time-reversal symmetry. Magnetic WSMs that arise from broken time-reversal symmetry provide an exceptional platform to understand the interplay between magnetic order and Weyl physics, but few WSMs have been realized. Here, we identify CeAlSi as a new non-centrosymmetric magnetic WSM via angle-resolved photoemission spectroscopy (ARPES) and first-principles, density-functional theory based calculations. Our surface-sensitive vacuum ultraviolet ARPES data confirms the presence of surface Fermi arcs as, the smoking gun evidence for the existence of the Weyl semimetallic state in CeAlSi. We also observe bulk Weyl cones in CeAlSi using bulk-sensitive soft-X-ray ARPES measurements. In addition, Ce 4f at bands are found near the Fermi level, indicating that CeAlSi is a unique platform for investigating exotic quantum phenomena resulting from the interaction of topology, magnetism and electronic correlations.

[1]  J. Gaudet,et al.  Weyl-mediated helical magnetism in NdAlSi , 2021, Nature Materials.

[2]  H. Yang,et al.  Picoscale Magnetoelasticity Governs Heterogeneous Magnetic Domains in a Noncentrosymmetric Ferromagnetic Weyl Semimetal , 2020, Advanced Quantum Technologies.

[3]  Xiegang Zhu,et al.  Kondo scenario of the γ–α phase transition in single crystalline cerium thin films , 2020, npj Quantum Materials.

[4]  Daniel S. Sanchez,et al.  Observation of Weyl fermions in a magnetic non-centrosymmetric crystal , 2020, Nature Communications.

[5]  J. Shim,et al.  Large anomalous Hall current induced by topological nodal lines in a ferromagnetic van der Waals semimetal , 2018, Nature Materials.

[6]  H. Weng,et al.  Large intrinsic anomalous Hall effect in half-metallic ferromagnet Co3Sn2S2 with magnetic Weyl fermions , 2017, Nature Communications.

[7]  Benedikt Ernst,et al.  A three-dimensional magnetic topological phase , 2017, 1712.09992.

[8]  C. Felser,et al.  Giant anomalous Hall effect in a ferromagnetic Kagomé-lattice semimetal , 2017, Nature Physics.

[9]  Su-Yang Xu,et al.  Discovery of Lorentz-violating type II Weyl fermions in LaAlGe , 2017, Science Advances.

[10]  Claudia Felser,et al.  Topological Materials: Weyl Semimetals , 2016, 1611.04182.

[11]  W. Duan,et al.  Experimental observation of topological Fermi arcs in type-II Weyl semimetal MoTe2 , 2016, Nature Physics.

[12]  P. Canfield,et al.  Use of frit-disc crucibles for routine and exploratory solution growth of single crystalline samples , 2015, 1509.08131.

[13]  Su-Yang Xu,et al.  Discovery of a Weyl fermion state with Fermi arcs in niobium arsenide , 2015, Nature Physics.

[14]  Yevhen Kushnirenko,et al.  Time-reversal symmetry breaking type-II Weyl state in YbMnBi2 , 2019, Nature Communications.

[15]  Xi Dai,et al.  Type-II Weyl semimetals , 2015, Nature.

[16]  X. Dai,et al.  Observation of Weyl nodes in TaAs , 2015, Nature Physics.

[17]  Shuang Jia,et al.  Discovery of a Weyl fermion semimetal and topological Fermi arcs , 2015, Science.