Triple-Point Fermions in Ferroelectric GeTe

Ferroelectric α-GeTe is unveiled to exhibit an intriguing multiple nontrivial topology of the electronic band structure due to the existence of triple-point and type-II Weyl fermions, which goes well beyond the giant Rashba spin splitting controlled by external fields as previously reported. Using s...

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Bibliographic Details
Published in:Physical review letters 2021-05, Vol.126 (20), p.206403-206403, Article 206403
Main Authors: Krempaský, Juraj, Nicolaï, Laurent, Gmitra, Martin, Chen, Houke, Fanciulli, Mauro, Guedes, Eduardo B, Caputo, Marco, Radović, Milan, Volobuev, Valentine V, Caha, Ondřej, Springholz, Gunther, Minár, Jan, Dil, J Hugo
Format: Article
Language:English
Subjects:
Brillouin zones
Condensed Matter
Condensed matter physics
Density functional theory
Fermions
Ferroelectric crystals
Ferroelectric materials
Ferroelectricity
Materials Science
Photoelectric emission
Physics
Point pairs
Topology
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Summary:Ferroelectric α-GeTe is unveiled to exhibit an intriguing multiple nontrivial topology of the electronic band structure due to the existence of triple-point and type-II Weyl fermions, which goes well beyond the giant Rashba spin splitting controlled by external fields as previously reported. Using spin- and angle-resolved photoemission spectroscopy combined with ab initio density functional theory, the unique spin texture around the triple point caused by the crossing of one spin-degenerate and two spin-split bands along the ferroelectric crystal axis is derived. This consistently reveals spin winding numbers that are coupled with time-reversal symmetry and Lorentz invariance, which are found to be equal for both triple-point pairs in the Brillouin zone. The rich manifold of effects opens up promising perspectives for studying nontrivial phenomena and multicomponent fermions in condensed matter systems.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.126.206403