Magnetic Breakdown Reshapes Quantum-Oscillation Phases in Kagome Metals

Abstract

Recent quantum-oscillation experiments on kagome metals have revealed markedly different phase responses even among systems with nearly identical band structures and Fermi-surface geometries. Using a tight-binding model, we show that weak orbital hybridization can slightly modify the hybridization gaps between neighboring orbits. These slight gap changes strongly reshape the measured oscillation phase, although the overall electronic structure remains nearly unchanged. This phase shift originates from magnetic breakdown, which reorganizes semiclassical trajectories and can mask the nontrivial phase of an isolated orbit, yielding a trivial phase response. Moreover, uniaxial strain can tune the hybridization gaps between neighboring orbits, thereby recovering the nontrivial phase response masked by magnetic breakdown and providing an experimentally accessible knob for controlling the oscillation phase. These results identify magnetic breakdown as the key mechanism controlling the phase response and provide a plausible explanation for recent experimental phase discrepancies in kagome metals.