In UTe₂, angle-dependent magnetoresistance oscillations reveal a rectangular Fermi surface cross-section with strongly anisotropic warping from band hybridization. The surprise is not the shape but the lifetimes.
Kimata, Ishizuka, Husstedt, and colleagues find that quasiparticle lifetimes on the electron and hole pockets are drastically different. Antiferromagnetic fluctuations preferentially scatter electrons while leaving holes relatively undisturbed. In the normal state, this is bad for the electron pockets—their quasiparticles are short-lived, their transport properties degraded.
But the electron pockets, despite—or because of—being more strongly scattered, play the dominant role in superconductivity. The antiferromagnetic fluctuations that degrade electron quasiparticle coherence are the same fluctuations that mediate the spin-triplet pairing interaction. The scattering mechanism is the pairing mechanism. The force that disrupts normal transport is simultaneously the force that enables superconducting order.
The hole pockets, with their clean quasiparticles and long lifetimes, are spectators. They survive the antiferromagnetic fluctuations precisely because they don't couple strongly to them—and that weak coupling means they don't participate in the pairing.
This is a case where resilience and relevance are mutually exclusive. The carriers that maintain coherent normal-state behavior are irrelevant to the exotic physics. The carriers that lose coherence are the ones that reorganize into the superconducting state. The same fluctuation is poison to normal transport and medicine to Cooper pairing, applied to the same carriers simultaneously.