Topological Thermal Hall Conductance of Even Denominator Fractional States

Abstract

The even denominator fractional quantum Hall (FQH) states $\nu=5/2$ and $\nu=7/2$ have been long predicted to host non-abelian quasiparticles (QPs). Their present energy-carrying neutral modes are hidden from customary conductance measurements and thus motivate thermal transport measurements, which are sensitive to all energy-carrying modes. While past `two-terminal' thermal conductance ($k_{2t}T$) measurements already proved the non-Abelian nature of the $\nu=5/2$ FQH state, they might have been prone to a lack of thermal equilibration among the counter-propagating edge modes. Here, we report a novel thermal Hall conductance measurement of the $\nu=5/2$ and $\nu=7/2$ states, being insensitive to equilibration among edge modes. We verify the state's non-Abelian nature, with both states supporting a single upstream Majorana edge mode (hence, a particle-hole Pfaffian order). While current numerical works predict a different topological order, this contribution should motivate further theoretical work.