Coherent mesoscopic transport, noise measurements, and electron-phono coupling in heavy fermion YbAl₃

YbAl₃ has a single-ion Kondo temperature of 670 K, with resistivity measurements suggesting a coherence onset scale for heavy fermion quasiparticles around T* ≈ 37 K. In nanowires etched from epitaxial films, we observe weak antilocalization magnetoresistance and universal conductance fluctuations at temperatures below 10K, consistent with coherence lengths of tens of nanometers. Johnson-Nyquist noise measurements indicate a significant electron-phonon coupling that increases with decreasing temperature. These measurements highlight the effectiveness of mesoscopic transport techniques in studying quasiparticles in correlated metals.