Indexed by: Journal paper

First Author: J-Z Ma

Correspondence Author: Ming Shi

Co-author: CJ Yi,Hong Ding,Tian Qian,YG Shi,Markus Müller,Christopher Mudry,Cesare Franchini,Michele Reticcioli,Joël Mesot,Wulf Wulfhekel,G Xu,Y-M Xiong,M Song,Marisa Medarde,SM Nie,Vladimir N Strocov,Alla Chikina,Yan Sun,LQ Yan,Muntaser Naamneh,Meng-Yu Yao,Tian Shang,Jasmin Jandke

Journal: Science advances

Included Journals: SCI

Discipline: Science

First-Level Discipline: Physics

Document Type: J

Volume: 5

Issue: 7

Page Number: eaaw4718

ISSN No.: 2375-2548

Date of Publication: 2019-07-12

Impact Factor: 13.117

Abstract: Weyl fermions as emergent quasiparticles can arise in Weyl semimetals (WSMs) in which the energy bands are nondegenerate, resulting from inversion or time-reversal symmetry breaking. Nevertheless, experimental evidence for magnetically induced WSMs is scarce. Here, using photoemission spectroscopy, we observe that the degeneracy of Bloch bands is already lifted in the paramagnetic phase of EuCd2As2. We attribute this effect to the itinerant electrons experiencing quasi-static and quasi–long-range ferromagnetic fluctuations. Moreover, the spin-nondegenerate band structure harbors a pair of ideal Weyl nodes near the Fermi level. Hence, we show that long-range magnetic order and the spontaneous breaking of time-reversal symmetry are not essential requirements for WSM states in centrosymmetric systems and that WSM states can emerge in a wider range of condensed matter systems than previously thought.