Direct magnetic imaging of fractional Chern insulators in twisted MoTe$_2$ with a superconducting sensor
Abstract: In the absence of time reversal symmetry, orbital magnetization provides a sensitive probe of topology and interactions, with particularly rich phenomenology in Chern insulators where topological edge states carry large equilibrium currents. Here, we use a nanoscale superconducting sensor to map the magnetic fringe fields in twisted bilayers of MoTe$_2$, where transport and optical sensing experiments have revealed the formation of fractional Chern insulator (FCI) states at zero magnetic field. At a temperature of 1.6K, we observe oscillations in the local magnetic field associated with fillings $\nu=-1,-2/3,-3/5,-4/7$ and $-5/9$ of the first moir\'e hole band, consistent with the formation of FCIs at these fillings. By quantitatively reconstructing the magnetization, we determine the local thermodynamic gaps of the most robust FCI state at $\nu=-2/3$, finding ${-2/3}\Delta$ as large as 7 meV. Spatial mapping of the charge density- and displacement field-tuned magnetic phase diagram further allows us to characterize sample disorder, which we find to be dominated by both inhomogeneity in the effective unit cell area as well as inhomogeneity in the band edge offset and bound dipole moment. Our results highlight both the challenges posed by structural disorder in the study of twisted homobilayer moir\'e systems and the opportunities afforded by the remarkably robust nature of the underlying correlated topological states.
- J. Cai, E. Anderson, C. Wang, X. Zhang, X. Liu, W. Holtzmann, Y. Zhang, F. Fan, T. Taniguchi, K. Watanabe, Y. Ran, T. Cao, L. Fu, D. Xiao, W. Yao, and X. Xu, “Signatures of Fractional Quantum Anomalous Hall States in Twisted MoTe2 Bilayer,” (2023).
- Z. Ji, H. Park, M. E. Barber, C. Hu, K. Watanabe, T. Taniguchi, J.-H. Chu, X. Xu, and Z.-x. Shen, “Local probe of bulk and edge states in a fractional Chern insulator,” (2024), arXiv:2404.07157 [cond-mat].
- Z. Lu, T. Han, Y. Yao, A. P. Reddy, J. Yang, J. Seo, K. Watanabe, T. Taniguchi, L. Fu, and L. Ju, “Fractional Quantum Anomalous Hall Effect in a Graphene Moire Superlattice,” (2023), arXiv:2309.17436 [cond-mat].
- N. Morales-Durán, N. Wei, J. Shi, and A. H. MacDonald, “Magic Angles and Fractional Chern Insulators in Twisted Homobilayer TMDs,” (2023), arXiv:2308.03143 [cond-mat].
- Y. Jia, J. Yu, J. Liu, J. Herzog-Arbeitman, Z. Qi, N. Regnault, H. Weng, B. A. Bernevig, and Q. Wu, “Moir\’e Fractional Chern Insulators I: First-principles calculations and Continuum Models of Twisted Bilayer MoTe$_2$,” (2023), arXiv:2311.04958 [cond-mat].
- D. N. Sheng, A. P. Reddy, A. Abouelkomsan, E. J. Bergholtz, and L. Fu, “Quantum anomalous Hall crystal at fractional filling of moir\’e superlattices,” (2024), arXiv:2402.17832 [cond-mat].
- J. Dong, T. Wang, T. Wang, T. Soejima, M. P. Zaletel, A. Vishwanath, and D. E. Parker, “Anomalous Hall Crystals in Rhombohedral Multilayer Graphene I: Interaction-Driven Chern Bands and Fractional Quantum Hall States at Zero Magnetic Field,” (2023b), arXiv:2311.05568 [cond-mat].
- T. Soejima, J. Dong, T. Wang, T. Wang, M. P. Zaletel, A. Vishwanath, and D. E. Parker, “Anomalous Hall Crystals in Rhombohedral Multilayer Graphene II: General Mechanism and a Minimal Model,” (2024), arXiv:2403.05522 [cond-mat].
- T. Arp, O. Sheekey, H. Zhou, C. L. Tschirhart, C. L. Patterson, H. M. Yoo, L. Holleis, E. Redekop, G. Babikyan, T. Xie, J. Xiao, Y. Vituri, T. Holder, T. Taniguchi, K. Watanabe, M. E. Huber, E. Berg, and A. F. Young, “Intervalley coherence and intrinsic spin-orbit coupling in rhombohedral trilayer graphene,” (2023), arXiv:2310.03781 [cond-mat].
- J. K. Jain, Physical Review Letters 63, 199 (1989), publisher: American Physical Society.
- R. Morf and B. I. Halperin, Physical Review B 33, 2221 (1986).
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