2020, Schindler, Clemens, Gorbunov, Denis, Zherlitsyn, Sergei, Galeski, Stanislaw, Schmidt, Marcus, Wosnitza, Jochen, Gooth, Johannes

In this study, we report on the observation of de Haas-van Alphen-type quantum oscillations (QOs) in the ultrasound velocity of NbP as well as "giant QOs"in the ultrasound attenuation in pulsed magnetic fields. The difference in the QO amplitude for different acoustic modes reveals a strong anisotropy of the effective deformation potential, which we estimate to be as high as 9eV for certain parts of the Fermi surface. Furthermore, the natural filtering of QO frequencies and the tracing of the individual Landau levels to the quantum limit allows for a more detailed investigation of the Fermi surface of NbP, as was previously achieved by means of analyzing QOs observed in magnetization or electrical resistivity. © 2020 authors. Published by the American Physical Society.

2023, Facio, Jorge I., Nocerino, Elisabetta, Fulga, Ion Cosma, Wawrzynczak, Rafal, Brown, Joanna, Gu, Genda, Li, Qiang, Mansson, Martin, Sassa, Yasmine, Ivashko, Oleh, von Zimmermann, Martin, Mende, Felix, Gooth, Johannes, Galeski, Stanislaw, van den Brink, Jeroen, Meng, Tobias

Real-world topological semimetals typically exhibit Dirac and Weyl nodes that coexist with trivial Fermi pockets. This tends to mask the physics of the relativistic quasiparticles. Using the example of ZrTe5, we show that strain provides a powerful tool for in-situ tuning of the band structure such that all trivial pockets are pushed far away from the Fermi energy, but only for a certain range of Van der Waals gaps. Our results naturally reconcile contradicting reports on the presence or absence of additional pockets in ZrTe5, and provide a clear map of where to find a pure three-dimensional Dirac semimetallic phase in the structural parameter space of the material.