Spin fluctuation induced Weyl semimetal state in the paramagnetic phase of EuCd$_2$As$_2$
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 EuCdAs. We attribute this effect to the itinerant electrons experiencing quasistatic 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 an essential requirement for WSM states in centrosymmetric systems, and that WSM states can emerge in a wider range of condensed-matter systems than previously thought.
Keywords
Cite
@article{arxiv.1907.05956,
title = {Spin fluctuation induced Weyl semimetal state in the paramagnetic phase of EuCd$_2$As$_2$},
author = {J. -Z. Ma and S. M. Nie and C. J. Yi and J. Jandke and T. Shang and M. Y. Yao and M. Naamneh and L. Q. Yan and Y. Sun and A. Chikina and V. N. Strocov and M. Medarde and M. Song and Y. -M. Xiong and G. Xu and W. Wulfhekel and J. Mesot and M. Reticcioli and C. Franchini and C. Mudry and M. Müller and Y. G. Shi and T. Qian and H. Ding and M. Shi},
journal= {arXiv preprint arXiv:1907.05956},
year = {2019}
}
Comments
34 pages,12 figures