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Condensed Matter Journal Club: Unoccupied topological surface states of magnetic Weyl semimetal candidate EuCd2As2

Event Type
Seminar/Symposium
Sponsor
Condensed Matter Journal Club
Location
Loomis 222
Date
Nov 6, 2024   3:00 pm  
Speaker
Rishi Acharya (UIUC)
Contact
Amanda Gatto Lamas
E-Mail
amandag6@illinois.edu
Views
9
Originating Calendar
Physics - Condensed Matter Journal Club

Identification of magnetic Weyl semimetals, in which time-reversal symmetry breaking allows the formation of a single pair of Weyl points in centrosymmetric materials, is a central goal of much experimental work. The topological nature of EuCd2As2, initially predicted and observed to be such a semimetal, has been under vigorous debate, with some recent studies characterizing it as a trivial magnetic semiconductor. Here, using time- and angle-resolved photoemission spectroscopy on ferromagnetically stabilized EuCd2As2, we directly observe a Weyl point 50 meV above the Fermi energy. We subsequently optically induce interband transitions to reveal an unoccupied topological surface state above the Fermi energy, and observe the formation of long-lived noninteracting quasiparticles therein at high excitation densities.

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