Speaker
Description
Twisting in van der Waals heterostructures has proven itself as indispensable in engineering new technologies with bespoke properties, from the tuning of proximity effects and spin transport to the enabling of superconductivity and non-trivial topology [1-4]. Twisted bilayer graphene has been the forerunner in our exploration of twistronics, but twisting in non-honeycomb systems has now become a new focal point in the field [5,6]. Most recently, twisted bilayer kagome (TBK) has emerged as a new point of interest due to the appearance of kagome patterning and physics in metal-organic frameworks and rare-Earth compounds [7,8]. The study of small incommensurate twists from a continuum perspective has relied heavily on the Bistritzer-MacDonald (BM) formalism to construct a moiré Hamiltonian. This method requires a non-extended Fermi surface, making application to TBK more challenging due to the kagome monolayer’s flat band.
In this talk, we extend the BM model to arbitrary twisted bilayer systems and apply it to TBK near 1/3 filling. We demonstrate an approximate particle-hole symmetry in TBK and show that TBK possesses higher-order magic angles corresponding to the onset of higher-order Van Hove singularities, evidenced by a drastic reduction in the renormalised Fermi velocity. We further discuss the topology of the emergent moiré bands and the role of sublattice interference at finite temperature.
Acknowledgements
D.T.S.P. and J.J.B. acknowledge funding from EPSRC: Grant Nos. EP/X012557/1 and EP/T034351/1.
References
[1] C.G. Péterfalvi et al., Phys. Rev. Research 4, L022049 (2022).
[2] D.T.S. Perkins et al., Phys. Rev. B 109, L241404 (2024).
[3] Y. Cao et al., Nature 556, 43 (2018).
[4] Z. Song et al., Phys. Rev. Lett. 123, 036401 (2019).
[5] X. Zhou et al., Phys. Rev. Lett. 133, 236401 (2024).
[6] D.T.S. Perkins et al., Phys. Rev. B 112, 235134 (2025).
[7] M. Fusch et al., J. Phys. Mater. 3, 025001 (2020).
[8] Y.E. Vekovshinin et al., ACS Nano 19, 36510 (2025).