Electrical Transport in Multilayer Twisted Graphene Homojunctions

In recent years, two-dimensional moire systems have emerged as a highly tunable playground for studying correlated physics. Superconductivity, correlated insulators and metals and ferromagnetism, among other phases, were first observed in twisted bilayer graphene (TBG). However, this characteristic abundance of interesting phases is not limited only to TBG but has also been shown in other graphene systems, including twisted double bilayer graphene, twisted trilayer graphene, and ABC-trilayer graphene. Here, we will report on our experimental work on multilayer twisted graphene homojunctions. We construct alternative-angle twisted stacks of graphene up to 4 layers. To untangle the relationship between these strongly correlated phases and the symmetries and properties of moire flat bands, we use the available experimental knobs of doping, displacement field, electric and magnetic fields, and temperature. We identify superconductivity and flavour ferromagnetism in these multilayer twisted graphene structures tuned by displacement fields as well as carrier densities. We will discuss our efforts to extend the family of moire materials by tuning the number of layers and stacking order in search of new strongly correlated physics.