Andrzej PTOK (Polish Academy of Sciences)
- 09 Nov 2023
- 11h00 - 12h00
A.PTOK: Electronic band structure – Experimental observations v. theoretical calculations
Angle-resolved photoemission spectroscopy (ARPES) gives the opportunity to directly study the electronic band structure. The ARPES spectra can usually be well reproduced by ab-initio (DFT) calculations. I will present our recent investigations of the electronic band structure for several compounds where this does not seem to be the case.
First, I will discuss half-Heusler compounds, which can possess non-trivial topological features similar to those observed in HgTe/CdTe, in particular YPdBi/YPtBi as an example of a trivial/topological compound . Next, I will discuss electronic band structure of GdTe3 antiferromagnet, with charge density wave (CDW). A large difference between theoretical and experimental results uncovers directly the momentum-dependent CDW gap . Finally, I will discuss the electronic band structure of an altermagnetic system. Altermagnets, as a third “new” elementary class of crystal with a collinear magnetic order, exhibit unconventional alternating spin-polarization and time-reversal-symmetry breaking in their band structure without magnetization. As an example I’ll discuss RuO3, where spin-polarized ARPES can be used as to test for existence of altermagnetism .
 “Tuning the topological character of half-Heusler systems YTBi (T=Pd, Pt)”,
J. C. Souza, M. V. Ale Crivillero, H. Dawczak-Debicki, A. Ptok, P. G. Pagliuso, and S. Wirth, Physical Review B 108, 165154 (2023).
 “Observation of momentum-dependent charge density wave gap in a layered antiferromagnet GdTe3”,
S. Regmi, I. Bin Elius, A. P. Sakhya, D. Jeff, M. Sprague, M. I. Mondal, D. Jarrett, N. Valadez, A. Agosto, T. Romanova, J.-H. Chu, S. I. Khondaker, A. Ptok, D. Kaczorowski, and M. Neupane, Scientific Reports 13, 18618 (2023).
 “Ruthenium dioxide RuO2: effect of the altermagnetism on the physical properties”,
A. Ptok, arXiv:2309.02421.