Abstract
The term chirality is derived from the Greek word for ‘hand’ χειρ (kheir) and describes objects that are distinct from their mirror image. It is long known that chirality plays a crucial role in nature, providing powerful functionality to chiral molecules in living organisms. By extending this concept from the molecular to the solid state, my group aims to uncover new chirality-enabled phenomena that could form the basis for new technologies.
The focus of my talk will be on chiral topological semimetals, a new class of quantum materials at the intersection of structural and electronic chirality. The first examples of this material class were discovered in 2019 (1–4), and since then, it has been demonstrated that they can host new fermionic quasiparticles without analogue in high-energy physics, which carry large and controllable topological charges (5). I will present new results beyond these initial works and demonstrate that these materials realize an isotropic Weyl-type parallel spin-momentum locking that can be considered the natural counterpart of Rashba spin-orbit coupling (6). Moreover, I will present fingerprints of controllable orbital angular momentum monopoles in these materials(7), which could be exploited in memory devices for field-free switching of magnets with perpendicular magnetic anisotropy.
Time permitting, I will also present our work on elucidating the origin of the magnetic field-induced (8) and field-free (9) Josephson diode effect. For the latter, we identify a momentum-resolved signature of Mottness that allows us to distinguish band- from unconventional Mott-insulators with an even number of electrons (10).
References
1. N. B. M. Schröter et al., Nat. Phys. 15, 759–765 (2019).
2. Z. Rao et al., Nature. 567, 496–499 (2019).
3. D. Takane et al., Phys. Rev. Lett. 122, 076402 (2019).
4. D. S. Sanchez et al., Nature. 567, 500–505 (2019).
5. N. B. M. Schröter et al., Science. 369, 179–183 (2020).
6. J. A. Krieger et al., Nat Commun. 15, 3720 (2024).
7. Y. Yen et al., Nat. Phys. (2024) 10.1038/s41567-024-02655-1
8. B. Pal et al., Nat. Phys. 18, 1228–1233 (2022).
9. H. Wu et al., Nature. 604, 653–656 (2022). 10. arXiv:2410.16199.
Biosketch
Since 2021, Dr. Niels B. M. Schröter has been leading an independent Max Planck Research Group at the Max Planck Institute of Microstructure Physics in Halle, Germany. He earned his DPhil in Physics from the University of Oxford in 2018, followed by postdoctoral research at the Paul Scherrer Institute in Switzerland. He is the recipient of the 2021 IBM Condensed Matter Physics Award for his discovery of chiral topological semimetals and holds an ERC Starting Grant to further explore this novel material class. His research spans the spectroscopy and synthesis of quantum materials, with a particular focus on structurally.
Please contact phweb@ust.hk should you have questions about the talk.
