Temperature Assisted Magnetic Breakdown in Moiré Bilayer Graphene

Magnetic breakdown, the semiclassical phenomenon in which Bloch electrons in a strong magnetic field tunnel between neighboring orbits, has long been studied in bulk systems at high magnetic fields. In 2D superlattice systems, we can make magnetic breakdown accessible at lower fields by decreasing the Brillouin Zone size and tuning the carrier density near a van Hove singularity, to bring Fermi pockets into close proximity. Previous work has observed magnetic breakdown among the higher valence and conduction bands in moiré bilayer graphene using nanoSQUID [1]. Here we report on magnetotransport signatures of magnetic breakdown in the first valence and conduction bands in moiré bilayer graphene, and carefully trace out the density and temperature dependence of magnetic breakdown in this system, uncovering the surprising result that the magnetic breakdown critical field decreases at elevated temperatures.