TY - JOUR
T1 - Experimental Realization of a Three-Dimensional Dirac Semimetal Phase with a Tunable Lifshitz Transition in Au2Pb
AU - Sánchez-Barriga, J.
AU - Clark, O. J.
AU - Vergniory, M. G.
AU - Krivenkov, M.
AU - Varykhalov, A.
AU - Rader, O.
AU - Schoop, L. M.
N1 - Publisher Copyright:
© 2023 American Physical Society.
PY - 2023/6/9
Y1 - 2023/6/9
N2 - Three-dimensional Dirac semimetals are an exotic state of matter that continue to attract increasing attention due to the unique properties of their low-energy excitations. Here, by performing angle-resolved photoemission spectroscopy, we investigate the electronic structure of Au2Pb across a wide temperature range. Our experimental studies on the (111)-cleaved surface unambiguously demonstrate that Au2Pb is a three-dimensional Dirac semimetal characterized by the presence of a bulk Dirac cone projected off-center of the bulk Brillouin zone (BZ), in agreement with our theoretical calculations. Unusually, we observe that the bulk Dirac cone is significantly shifted by more than 0.4 eV to higher binding energies with reducing temperature, eventually going through a Lifshitz transition. The pronounced downward shift is qualitatively reproduced by our calculations indicating that an enhanced orbital overlap upon compression of the lattice, which preserves C4 rotational symmetry, is the main driving mechanism for the Lifshitz transition. These findings not only broaden the range of currently known materials exhibiting three-dimensional Dirac phases, but also show a viable mechanism by which it could be possible to switch on and off the contribution of the degeneracy point to electron transport without external doping.
AB - Three-dimensional Dirac semimetals are an exotic state of matter that continue to attract increasing attention due to the unique properties of their low-energy excitations. Here, by performing angle-resolved photoemission spectroscopy, we investigate the electronic structure of Au2Pb across a wide temperature range. Our experimental studies on the (111)-cleaved surface unambiguously demonstrate that Au2Pb is a three-dimensional Dirac semimetal characterized by the presence of a bulk Dirac cone projected off-center of the bulk Brillouin zone (BZ), in agreement with our theoretical calculations. Unusually, we observe that the bulk Dirac cone is significantly shifted by more than 0.4 eV to higher binding energies with reducing temperature, eventually going through a Lifshitz transition. The pronounced downward shift is qualitatively reproduced by our calculations indicating that an enhanced orbital overlap upon compression of the lattice, which preserves C4 rotational symmetry, is the main driving mechanism for the Lifshitz transition. These findings not only broaden the range of currently known materials exhibiting three-dimensional Dirac phases, but also show a viable mechanism by which it could be possible to switch on and off the contribution of the degeneracy point to electron transport without external doping.
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U2 - 10.1103/PhysRevLett.130.236402
DO - 10.1103/PhysRevLett.130.236402
M3 - Article
C2 - 37354399
AN - SCOPUS:85162740657
SN - 0031-9007
VL - 130
JO - Physical review letters
JF - Physical review letters
IS - 23
M1 - 236402
ER -