Dr. Anna M. Seiler, ETH Zurich, Switzerland

Leuchs-Russell-Auditorium, A.1.500, Staudtstr. 2, Erlangen

Location Details

Abstract

Two-dimensional (2D) materials have emerged as a powerful platform for exploring quantum many-body interactions. Through van der Waals heterostructure design and electrostatic gating, their band structure can be engineered and tuned in situ, providing controlled access to correlation-driven electronic and excitonic phases.

In Bernal bilayer graphene, we investigate how this tunability gives rise to interactiondriven electronic phases. Electric-field-controlled Lifshitz transitions near van Hove singularities strongly enhance electronic correlations, leading to fractional Stoner-type metals as well as competing insulating and metallic phases. These states manifest in characteristic transport signatures, revealing the delicate interplay between band structure and interactions in a simple, gate-tunable system [1–4].

Complementarily, transition-metal dichalcogenide (TMD) heterobilayers provide access to interacting bosonic degrees of freedom in the form of interlayer excitons—spatially separated electron–hole pairs with long lifetimes and strong Coulomb binding. Using optical exciton injection combined with time-resolved optical reflectance spectroscopy, we probe interlayer exciton dynamics and observe lifetimes of up to eight microseconds in hBN-spaced TMD bilayers [5].

Together, these results highlight the rich landscape of correlation-driven quantum phases in 2D materials, ranging from electronic order in bilayer graphene to collective excitonic states in TMD heterostructures. Furthermore, they position 2D heterostructures as a versatile platform for exploring coupled Bose–Fermi physics. In hybrid graphene–TMD systems, fermionic charge carriers can interact with a tunable reservoir of bosonic interlayer excitons, enabling the investigation of new regimes of correlated electronic behavior driven by exciton-mediated coupling [6,7].

References:
[1] A. M. Seiler et al., Nature 608, 298–302 (2022).
[2] A. M. Seiler et al., Nat. Commun. 15, 3133 (2024).
[3] A. M. Seiler et al., Phys. Rev. Le4. 133, 066301 (2024).
[4] A. M. Seiler et al., Nat. Commun. 16, 8921 (2025).
[5] A. Tugen*, A. M. Seiler* et al., Phys. Rev. Le4. 135, 246502 (2025).
[6] J. von Milczewski et al., Phys. Rev. Le4. 133, 226903 (2024).
[7] C. Zerba et al., Phys. Rev. Le4. 133, 056902 (2024).