29–30 Oct 2019
FHNW Brugg
Europe/Zurich timezone

Spin uctuation induced Weyl semimetal state in the paramagnetic phase of EuCd2As2

29 Oct 2019, 14:00
30m
FHNW Brugg

FHNW Brugg

Speaker

Dr J.-Z. Ma (Paul Scherrer Institut)

Description

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 eff?ect 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.

Position Postdoc

Primary author

Dr J.-Z. Ma (Paul Scherrer Institut)

Co-authors

Dr J. Jandke (Paul Scherrer Institut) Dr T. Shang (Paul Scherrer Institut,) Prof. M. Medarde (Laboratory for Multiscale Materials Experiments, Paul Scherrer Institute) Prof. J. Mesot (Paul Scherrer Institut) Prof. Y. G. Shi (Institute of Physics, Chinese Academy of Sciences) Prof. T. Qian (Institute of Physics, Chinese Academy of Sciences) Prof. H. Ding (Institute of Physics, Chinese Academy of Sciences) Prof. C. Mudry (4Condensed Matter Theory Group, Paul Scherrer Institut) Prof. M. Müller (4Condensed Matter Theory Group, Paul Scherrer Institut) Prof. M. Shi (Paul Scherrer Institut)

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