Experimental Evidence of Electron‐enhanced Interfacial Thermal Conductance Through Two‐Dimensional Electron Gas

Abstract It has been a persistent challenge to experimentally distinguish the contribution of electron‐phonon coupling on interfacial thermal conductance from phonon‐dominated pathways. The LaAlO 3 /SrTiO 3 (LAO/STO) interface offers a unique platform to address this, at which two‐dimensional electron gas (2DEG) can be formed or absent depending on whether the LAO is terminated by TiO 2 or SrO during the growth, and enables a direct comparison of thermal transport with and without interfacial free electrons. Using time‐domain thermoreflectance measurements, it is demonstrated that the interfacial thermal conductance is enhanced by 35–40% in the 2DEG‐active interface compared to its 2DEG‐free counterpart. This enhancement provides direct experimental evidence of electron‐phonon coupling as an additional thermal transport channel, distinct from phonon contributions. The extracted electron‐phonon coupling coefficient (G≈10 16 W m −3 K −1 ) aligns with the first‐principles predictions for oxide interfaces. Crucially, the results resolve the long‐standing ambiguity in decoupling electronic and phononic thermal pathways, offering a generalizable framework to quantify electron‐phonon interactions at metal‐dielectric heterointerfaces.