Simon Munyan: Ballistic Chiral Heat Transport in Cd3As2 Quantum Wells

Simon Munyan: Ballistic Chiral Heat Transport in Cd3As2 Quantum Wells

Abstract: Two-dimensional electron systems in a strong magnetic field exhibit the integer quantum Hall effect, where charge and energy are carried by one-dimensional chiral edge modes. While the edge modes transport charge without backscattering over macroscopic distances, ballistic heat transport has not been observed over comparable distances, for reasons that are not fully understood. In this talk, we examine the thermal transport of chiral edge modes via their thermoelectric responses, using hot-electron injection in Cd 3 As 2 quantum wells. We find that the edge modes carry heat downstream from the source, giving rise to a finite thermoelectric signal in the Landau levels that agrees qualitatively with the Mott formula. Heat transport follows the chirality of the edge modes. Thermal transport via a single edge mode is ballistic over distances exceeding 800 μm in a quantum Hall plateau, much farther than in other 2D systems. We attribute this difference to strongly suppressed electron-phonon coupling in Cd 3 As 2 quantum wells. We also observe an absence of heat equilibration among co-propagating edge modes, despite complete charge equilibration. The results point to the importance of interactions among the edge modes, which should motivate future theoretical studies.