Speaker: Yi-Ting Hsu (Notre Dame) Title: Van Hove–Driven Symmetry-Broken Phases in Few-Layer van der Waals Systems Abstract: Few-layer van der Waals materials offer a versatile platform to investigate correlated quantum phases. A central theme in both twisted and untwisted graphene and transition metal dichalcogenides systems is the emergence of Van Hove singularities (VHS), which strongly enhance electronic interactions and can drive competing orders.
In this talk, I will discuss the symmetry-broken phases that intra- and inter-VHS interactions alone can mediate within a renormalization group framework, independent of the Fermi surface details. By tuning the number and type of VHS—through spin-orbit coupling, external fields, or twist angle—one can further engineer controlled phase transitions. I will illustrate this mechanism in three case studies: twisted double bilayer graphene, twisted Bernal bilayer graphene proximitized by WSe, and twisted bilayer WSe, and discuss experimental probes that can test these predictions. Our findings highlight VHS fermiology as a general strategy to design and control exotic phases in two-dimensional quantum materials.