Fermionic Critical Fluctuations: Potential Driver of Strange Metallicity and Violation of the Wiedemann-Franz Law in YbRh₂Si₂

Results of combined thermal and electrical transport measurements through the magnetic field-induced quantum critical point (QCP) in the heavy-fermion compound YbRh₂Si₂ were revisited to explore the relationship between the strange-metal behavior observed in electrical and electronic thermal resistivities and the violation of the Wiedemann-Franz (WF) law in the zero-temperature limit. A new type of inelastic scattering center for the charge and heat carriers was detected, attributed to small-to-large Fermi surface fluctuations operating near the Kondo-destroying QCP. These fermionic quantum critical fluctuations are considered the primary driver of the strange-metal behavior and the violation of the WF law.