Tunable correlated states in small angle twisted double bilayer graphene device

  T R Devidas  ,  Hadar Steinberg  
Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel

The inter-layer twist degree of freedom accomplished in van der Waals heterostructure devices, has permitted the realisation of a variety of fundamental ground states in such systems. In the present work, we study a small angle Twisted Double Bilayer Graphene [TDBG] device, built using the van der waals tear and stack method. The Moire potentials resulting from the small twist angle of ~ 0.9 degrees lead to several correlated flat bands in the electronic structure. We observe prominent fillings at ±1 ns and ±3 ns. Tuning the applied in-situ displacement fields leads to the observation of correlated states at ± 2ns and weak signatures of states at (-1/4 ns) and (-1/2 ns) filling. We observe weak signatures of symmetry-breaking via non-linear current-voltage relations, hinting at non-trivial topologies at zero magnetic field.