Berlin 2024 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 8: INNOMAG e.V. Prizes 2024 (Diplom-/Master and Ph.D. Thesis)
MA 8.7: Vortrag
Montag, 18. März 2024, 17:30–17:55, H 1058
Exploring ultrafast dynamics of electrons in heavy-fermion materials by THz time-domain spectroscopy — •Chia-Jung Yang and Manfred Fiebig — Department of Materials, ETH Zurich, Switzerland
The development of novel states of matter is a significant aspect of modern physics, with quantum phase transitions (QPT) playing a crucial role. These transitions are dominated by quantum fluctuations of magnetic and electronic degrees, giving rise to new behavior emerging near the quantum-critical point. Heavy-fermion materials, which exhibit strong coupling between magnetic and electronic properties, serve as an ideal platform for exploring these phenomena. This work utilizes terahertz time-domain spectroscopy (THz-TDS) to investigate the ultrafast electronic dynamics across QPTs in such materials. THz-TDS, effective in probing low-energy excitations, illuminates the dynamics of quasiparticles and provides direct access to information that was otherwise not accessible before [1]. In prototypical heavy-fermion materials, we have thus discovered novel types of quantum-matter dynamics. Specifically, in YbRh2Si2, we observed the first example of critical slowing down in a fermionic system close to a QPT [2]. In CeCu6−xAux, we distinguished two different correlated contributions to the optical conductivity [3] and identified lattice coherence in the form of heavy-fermion formation from optical coherence in the form of superradiance.
[1] Nat. Rev. Mater 8, 518 (2023).
[2] Nat. Phys. 19, 1605 (2023).
[3] Phys. Rev. Research 2, 033296 (2020)
Keywords: THz spectroscopy; Heavy-fermion materials; Quantum phase transitions