Quantum oscillations of the quasiparticle lifetime in a metal

The low-lying excitations of metals are remarkably well explained by effective single-particle theories of non-interacting bands in which correlations are usually accounted for by a renormalization of the band properties. Here, we report a novel signature of interaction between two bands in the quantum oscillations (QOs) of the topological semimetal CoSi [1]. Its remarkably simple, well understood QO spectrum [2-4] allows us to identify a QO frequency which defies the standard description in two ways. First, the frequency corresponds to the difference of two conventional quasiparticle (QP) orbits although this combination is semi-classically forbidden. Second, the oscillations exist up to above 50 K - at which all other frequencies are completely suppressed. We show that our findings are in excellent agreement with QOs of the QP lifetime [5] which are expected to be a generic feature for any multiband metal featuring Landau quantization. We discuss further materials in which QOs of the QPL may have unknowingly been observed before.

[1] N. Huber et al., Nature 621, 276-281 (2023)

[2] N. Huber et al., Phys. Rev. Lett. 129, 026401 (2022)

[3] C. Guo et al., Nat. Phys. 18, 813 (2022)

[4] N. Huber et al., Phys. Rev. B 109, 205115 (2024)

[5] Leeb et al., Phys. Rev. B 108, 054202 (2023)