In a strong magnetic field, electrons in a thin metal film move along circular orbits. When the film thickness is comparable to the size of such an orbit, the resistance starts to oscillate: these are Sondheimer oscillations, known since the mid-20th century as a purely geometric effect. New research shows that quantum corrections tied to the topology of electron bands change the frequency of these oscillations.
The authors developed a general quantum theory for thin conductors in the high-magnetic-field limit. Unlike Shubnikov–de Haas oscillations, where topology enters only through the phase, here it shifts the frequency itself. This allows direct reconstruction of the full Landau level spectrum, the allowed energies of an electron in a magnetic field, without complex fitting.
A model with tunable Berry phase demonstrates how topology shows up in experimentally accessible magnetoresistance spectra. The damping of oscillations due to surface roughness, an important factor for real samples, is also considered.
as written by the authors arXiv:2604.10141
Sondheimer oscillations (SO) are magnetoresistance oscillations occurring in thin films due to the commensurability between cyclotron motion and sample thickness, and are traditionally regarded as a purely semiclassical size effect. Here we develop a general quantum theory of SO for thin-film conductors in the quantum limit of a large magnetic field. We show that corrections arising from band topology modify the SO frequency, in contrast to Shubnikov-de Haas oscillations where topological information appears only in the phase. As a consequence, quantum SO provide a direct and robust probe of the full Landau level spectrum. Applying our framework to a minimal model with tunable Berry phase, we demonstrate how topology manifests itself in experimentally accessible magneto-oscillation spectra and discuss damping mechanisms including surface roughness.
Sondheimer oscillations are named after the physicist who in 1950 explained them as interference of electron waves reflected from the film boundaries.