Unconventional quantum oscillations in focused ion beam prepared microstructures of ZrSiS

Investigating the role played by topology in the electronic behavior of quantum materials requires detailed understanding of the Fermi surface. Magneto-quantum oscillations are a well-established method to study the Fermi surface and the resultant electronic properties, even for complex systems. The observation of extremal orbits on the Fermi surface using quantum oscillations requires low temperatures and high magnetic fields, but even more critical is the availability of high-quality single crystals. Any impurities, mosaicity, or strain can lead to decoherence or changes in the Fermi surface, washing out the spectrum of oscillation frequencies. The Dingle factor describes this exponential dependence of oscillation amplitude due to electronic scattering. Using a focused ion beam to microstructure materials, we create strain-free devices that preserve the high quality of bulk single crystals and enhance the Dingle term thereby allowing us to study higher order scattering phenomena. Here we present a magneto-quantum oscillation study of the topological semimetal ZrSiS, a particularly strain sensitive material [1] with a nodal line threading through its Fermi surface. The interplay between its complex Fermi surface, the linear electronic dispersion near the Fermi level, and low spin-orbit coupling gives rise to a rich quantum oscillation spectrum [2]. With our unique strain-free microstructures, we can observe and explore these higher order effects, such as quasiparticle lifetime oscillations which are exponentially sensitive to the Dingle term. Thermodynamic probes are not sensitive to these phenomena, while conventional transport techniques struggle to observe them within typical noise levels. Our state-of-the-art fabrication and measurement techniques provide a window into these delicate phenomena, and a pathway towards new insights in magneto-quantum oscillations and the scattering channels that govern electronic behavior in quantum materials.

[1] Lorenz, et al. PRB 109, 235 114 (2024)

[2] Müller, et al. PRR 2, 023217 (2020)