Revealing the Thermal Properties of Superconducting Magic-Angle Twisted Bilayer Graphene.

Abstract

The allegedly unconventional superconducting phase of magic-angle twisted bilayer graphene (MATBG) has been predicted to possess extraordinary thermal properties, as it is formed from a highly diluted electron ensemble with a record-low carrier density (n) of ∼1011 cm-2 and electronic heat capacity (Ce) of <100kB. While these attributes position MATBG as a ground-breaking material platform for revolutionary calorimetric applications, these properties have so far not been experimentally shown. Here, we reveal the thermal properties of superconducting MATBG by monitoring its temperature dependent critical current (Ic) under continuous laser heating at 1550 nm. From the bolometric effect, we extract the temperature dependence of the electronic thermal conductance (Gth), which has a value of Gth = 0.2 pW/K at 35 mK and in the low temperature limit is consistent with a power law dependence, as expected for nodal superconductors. Our work lays the foundation for future thermal transport studies on this system.