By stacking atomically thin layers at a controlled twist angle, we engineer electronic band structures that are impossible in any single material. Our work in bilayer graphene\/hBN moir\u00e9 superlattices has uncovered a hierarchy of miniband gaps, emergent Dirac fermions, and new mechanisms for controlling electron-electron interactions \u2014 all with simple electrostatic gates.<\/p>\n\n\n\n
<\/p>\n\n\n\n
Some representative results are mentioned below: <\/p>\n\n\n\n
Non-uniform strain in graphene generates a pseudomagnetic field that acts on electrons like a real magnetic field but preserves time-reversal symmetry. While such fields have previously been visualised only by local probes, we demonstrate that high-mobility graphene exhibits distinct beating patterns in Shubnikov-de Haas oscillations arising from valley-resolved Landau quantization under different effective magnetic fields. Systematic analysis of the beating nodes reveals universal quadratic and linear scaling with applied magnetic field, enabling extraction of pseudomagnetic fields as small as a few millitesla. Our results establish quantum oscillation spectroscopy as a robust macroscopic transport probe of strain-induced gauge fields in Dirac materials, opening avenues for mechanically tunable valleytronic and straintronic devices.<\/p>\n\n\n\n
D. Sahani, S. Das, K. Watanabe, T. Taniguchi, A. Agarwal, Aveek Bid \u2014 Phys. Rev. Lett. 136, 166604 (2026)<\/a> | arXiv:2511.14888<\/a><\/p>\n\n\n\n Moir\u00e9 superlattices formed between bilayer graphene and hexagonal boron nitride are known to host a rich set of satellite Dirac points at the superlattice Brillouin zone boundaries. We demonstrate that hBN alignment induces a topological band reconstruction in bilayer graphene superlattices, generating secondary bands that host massless, chiral fermions while the primary band retains its massive chiral character. Magnetotransport measurements including quantum Hall, temperature-dependent Shubnikov-de Haas oscillations, and Berry phase analysis confirm the distinct topological nature of these bands. A significantly reduced Fermi velocity in the moir\u00e9 secondary band indicates band flattening induced by the moir\u00e9 potential.<\/p>\n\n\n\n M. K. Jat, K. Watanabe, T. Taniguchi, Aveek Bid \u2014 Phys. Rev. B 113, L081102 (2026)<\/a> | arXiv:2510.20309<\/a><\/p>\n\n\n\n When bilayer graphene is aligned with hBN on both sides, the two moir\u00e9 superlattices interfere to produce a hierarchy of miniband gaps at wavevectors corresponding to higher-order umklapp processes. We observe these higher-order gaps in transport and show that their magnitude significantly exceeds predictions based on a bare moir\u00e9 potential. This strong renormalization of the band structure arises from electron-electron interactions within the moir\u00e9 flat bands, demonstrating that correlation effects are crucial for understanding the electronic structure of doubly aligned devices.<\/p>\n\n\n\n M. K. Jat, P. Tiwari, R. Bajaj, I. Shitut, S. Mandal, K. Watanabe, T. Taniguchi, H. R. Krishnamurthy, M. Jain, Aveek Bid \u2014 Nat. Commun. 15, 2335 (2024)<\/a> | arXiv:2304.01720<\/a><\/p>\n\n\n\n Umklapp scattering \u2014 where electrons scatter with a momentum transfer equal to a reciprocal lattice vector \u2014 is normally a fixed property of a crystal. In a moir\u00e9 superlattice, the moir\u00e9 reciprocal lattice vectors are tunable through twist angle and gating. We demonstrate gate-controlled Umklapp scattering in a bilayer graphene moir\u00e9 device, showing that the strength of umklapp processes and the associated resistivity peak can be continuously tuned by a back-gate voltage. This provides a new, electrically controlled knob for engineering electron-electron interactions in moir\u00e9 systems.<\/p>\n\n\n\n M. K. Jat, S. Mishra, H. K. Mann, R. Bajaj, K. Watanabe, T. Taniguchi, H. R. Krishnamurthy, M. Jain, Aveek Bid \u2014 Nano Lett. 24, 2203 (2024)<\/a> | arXiv:2310.08906<\/a><\/p>\n","protected":false},"excerpt":{"rendered":" By stacking atomically thin layers at a controlled twist angle, we engineer electronic band structures that are impossible in any single material. Our work in bilayer graphene\/hBN moir\u00e9 superlattices has uncovered a hierarchy of miniband gaps, emergent Dirac fermions, and new mechanisms for controlling electron-electron interactions \u2014 all with simple electrostatic gates. Some representative results […]<\/p>\n","protected":false},"author":4,"featured_media":4475,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[41],"tags":[],"class_list":["post-4938","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-research"],"_links":{"self":[{"href":"https:\/\/physics.iisc.ac.in\/~aveek_bid\/wp-json\/wp\/v2\/posts\/4938","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/physics.iisc.ac.in\/~aveek_bid\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/physics.iisc.ac.in\/~aveek_bid\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/physics.iisc.ac.in\/~aveek_bid\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/physics.iisc.ac.in\/~aveek_bid\/wp-json\/wp\/v2\/comments?post=4938"}],"version-history":[{"count":2,"href":"https:\/\/physics.iisc.ac.in\/~aveek_bid\/wp-json\/wp\/v2\/posts\/4938\/revisions"}],"predecessor-version":[{"id":4948,"href":"https:\/\/physics.iisc.ac.in\/~aveek_bid\/wp-json\/wp\/v2\/posts\/4938\/revisions\/4948"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/physics.iisc.ac.in\/~aveek_bid\/wp-json\/wp\/v2\/media\/4475"}],"wp:attachment":[{"href":"https:\/\/physics.iisc.ac.in\/~aveek_bid\/wp-json\/wp\/v2\/media?parent=4938"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/physics.iisc.ac.in\/~aveek_bid\/wp-json\/wp\/v2\/categories?post=4938"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/physics.iisc.ac.in\/~aveek_bid\/wp-json\/wp\/v2\/tags?post=4938"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
\n\n\n\nCoexisting massive and massless Dirac fermions in moir\u00e9-reconstructed bilayer graphene Phys. Rev. B (2026)<\/a><\/h3>\n\n\n\n
\n\n\n\nHigher-order gaps in the renormalized band structure of doubly aligned hBN\/bilayer graphene moir\u00e9 superlattice Nature Communications (2024)<\/a><\/h3>\n\n\n\n
\n\n\n\nControlling Umklapp scattering in a bilayer graphene moir\u00e9 superlattice Nano Letters (2024)<\/a><\/h3>\n\n\n\n