Berlin 2024 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 59: Transport: Poster

TT 59.11: Poster

Mittwoch, 20. März 2024, 15:00–18:00, Poster E

Integer and fractional moiré Chern insulators in van der Waals bilayers — •Mirko Bacani, Rajarshi Bhattacharyya, and Florian Otto — attocube systems AG, Haar, Germany

Moiré van der Waals (vdW) materials have become established playground for exploring band topology and strong-correlations phenomena. Cryogenic nanopositioning and nanorotating setups of attocube systems are widely used in such nanoscale studies because they provide supreme stability and ultra-low-vibrations environment. These cryogenic scanning setups include confocal microscopes and various scanning probe microscopes.

We present here a selection of remarkable results achieved with attocube systems technology in labs of our customers with emphasis on integer and fractional moiré Chern insulators (MCIs) in vdW bilayers: Scanning magnetometry of an integer MCI MoTe₂/WSe₂ shows that its magnetization can be flipped with a very low current [1], which is appealing for utilization in energy-efficient magnetic memories. Magneto-optical study of the same heterostructure discovered a valley-nonpolarized quantum anomalous Hall state [2]. Magic angle twisted bilayer graphene (MATBG), identified as an integer MCI [3], reveals orbital magnetism induced by local Berry curvature as the function of the integer filling factor [4]. Moreover, MATBG can also exhibit fractional Chern insulating states (FCIS) even in low magnetic fields B<12T [5]. FCIS that survive in B=0 have been identified magneto-optically in twisted bilayer MoTe₂ using trions as the local probe for real-space imaging of spin polarization [6].

Keywords: Chern insulator; moiré; van der Waals; bilayer; cryogenic