论文类型：期刊论文
第一作者：J-Z Ma
通讯作者：Ming Shi
合写作者：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
发表刊物：Science advances
收录刊物：SCI
学科门类：理学
一级学科：物理学
文献类型：J
卷号：5
期号：7
页面范围：eaaw4718
ISSN号：2375-2548
发表时间：2019-07-12
影响因子：13.117
摘要：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.