{"id":4398,"date":"2025-02-20T00:17:10","date_gmt":"2025-02-19T23:17:10","guid":{"rendered":"https:\/\/equipes.lps.u-psud.fr\/puls\/?p=4398"},"modified":"2025-04-15T11:14:37","modified_gmt":"2025-04-15T09:14:37","slug":"band-engineering-in-2d-superlattices-with-rotation-symmetry-mismatched-interfaces","status":"publish","type":"post","link":"https:\/\/equipes.lps.u-psud.fr\/puls\/band-engineering-in-2d-superlattices-with-rotation-symmetry-mismatched-interfaces\/","title":{"rendered":"Band engineering in 2D superlattices with rotation-symmetry-mismatched interfaces"},"content":{"rendered":"\n

Two-dimensional (2D) moir\u00e9 superlattices, formed by stacking individual layers such as 2H transition metal dichalcogenides (TMDs) with accurately twisted angles, have garnered significant attention due to their potential to host phenomena due to strong electron correlations, including unconventional superconductivity, moir\u00e9 excitons, Wigner crystalline states, and orbital ferromagnetism. The moir\u00e9 potentials and flat bands play a key role in driving these correlated phenomena. However, several emergent aspects of the physics of TMDs-based moir\u00e9 superlattices remain unexplored. First, flat bands have so far only been observed at “magic” twisted angles and below the valence band maximum (VBM) in TMDs superlattices. Whether it is possible to generate flat bands at arbitrary angles and push these bands to the highest occupied states\u2014where novel quantum phenomena are expected to emerge\u2014remains an open challenge. Second, 2H TMDs hold three-fold rotational (C3<\/sub>) symmetry. The breaking of C3<\/sub> symmetry by stacking it on two-fold rotational symmetry (C2<\/sub>) layers such as black phosphorous can bring novel photovoltaic phenomena in 2H TMDs such as spontaneous photocurrent due to band hybridization between C3<\/sub> and C2<\/sub> layers. However, the physics behind the C3<\/sub> symmetry breaking and the detailed mechanism of band hybridization remains understudied to date. These questions can be effectively addressed via a direct visualization of the electronic band structure. New developments in micro angle-resolved photoemission spectroscopy (micro-ARPES) can now provide the necessary space resolution to study these heterostructures with the further advantage of providing both a high energy and momentum resolution.<\/p>\n\n\n\n

In this work, Z. Zhang et al. studied the first example of electronic band structure properties in a C3<\/sub> layer\/C2<\/sub> layer stacked superlattice, MoS2<\/sub>-black phosphorus. The atomic structure and the corresponding Brillouin zone of the superlattice with a twist angle of \u03b8 are shown in Fig. 1a<\/strong>. Regardless of the twist angles between MoS2<\/sub> and black phosphorus, a breaking of the C3<\/sub> symmetry for the highest occupied MoS2<\/sub> states is directly observed in the constant energy cut of 3D ARPES maps. This is demonstrated by comparing the pristine MoS2<\/sub> (MoS2<\/sub> on BN) with the MoS2<\/sub>-black phosphorus regions, as shown in Fig. 1b<\/strong>. Additionally, micro-ARPES reveals the formation of anisotropic flat bands and minigaps at the \u0393 valley, as seen in Fig. 1c<\/strong>, where these properties are highly dependent on the orientation of the underlying black phosphorus layer. Moreover, a giant energy renormalization of approximately 140 meV is visualized in Fig. 1d<\/strong>, leading to a shift of the VBM from the K point to the \u0393 point. All these effects are explained by Density Functional Theory (DFT) calculations, indicating that they arise from strong hybridization between the Mo dz2<\/sup><\/sub><\/em>  orbitals of the monolayer MoS2<\/sub> and the P px<\/sub><\/em> orbitals of the black phosphorous, as depicted in Fig. 1e<\/strong>. This understanding of the electronic structure modulation in monolayer MoS2<\/sub>, induced by the substrate black phosphorus through rotational symmetry breaking and interlayer hybridization, opens up novel possibilities for generating flat bands at arbitrary twist angles in 2D heterostructures and manipulating anisotropic properties in TMDs.<\/p>\n\n\n\n

\"Figure<\/figure>\n\n\n\n

Figure 1<\/strong>: a) The atomic structure and the corresponding Brillouin zone of the superlattice with a twist angle of \u03b8. (b) Constant energy cut maps of pristine monolayer MoS2<\/sub> (top panel) and MoS2<\/sub>-bP superlattices with \u03b8=8.5\u00b0 (bottom panel). (c) Valence bands of pristine monolayer MoS2<\/sub> and MoS2<\/sub>-bP along the armchair (AC), AC+45\u00b0 and zigzag (ZZ) directions in superlattices with \u03b8=8.5\u00b0. (d) Band renormalization between pristine MoS2<\/sub> and MoS2<\/sub> on black phosphorus. (e) The unfolded bands projected onto Mo dz2<\/sup><\/sub>  (cyan) and d<\/em>x2<\/sup>+y<\/em>2<\/sup><\/sub> (magenta) and P px<\/sub><\/em> orbitals (yellow) from DFT calculation. Adapted from Z. Zhang et al., Nat. Commun. 16<\/strong>, 763 (2025), with permission from Nature Communications.<\/p>\n\n\n\n

Micro-ARPES experiments were carried out at the Spectromicroscopy beamline<\/a> of Elettra using photons with energies of h\u03bd=27 eV and h\u03bd=74 eV. DFT calculations have been performed using the OpenMX code. The exchange-correlation potential was expressed in the generalized gradient approximation using the Perdew-Burke-Ernzerhof (PBE) schema. Norm conserving full relativistic pseudopotentials including a partial core correction and spin-orbit coupling was used. Dispersion interactions have been included using the Grimme-D2 method.<\/p>\n\n\n\n

Z. Zhang, A. Zobelli, C. Gao, Y. Cheng, J. Zhang, J. Caillaux, L. Qiu, S. Li, M. Cattelan, V. Kandyba, A. Barinov, M. Zaghrioui, A. Bendounan, J.-P. Rueff, W. Qi, L. Perfetti, E. Papalazarou, M. Marsi, Z. Chen, \u201cRotation Symmetry Mismatch and Interlayer Hybridization in MoS2-Black Phosphorus van der Waals Heterostructures\u201d<\/em>, Nat. Commun. 16<\/strong>, 763 (2025); DOI: 10.1038\/s41467-025-56113-4<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"

Two-dimensional (2D) moir\u00e9 superlattices, formed by stacking individual layers such as 2H transition metal dichalcogenides (TMDs) with accurately twisted angles, have garnered significant attention due to their potential to host …<\/p>\n","protected":false},"author":23,"featured_media":4399,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[13,15],"class_list":["post-4398","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news","tag-2d-materials","tag-synchrotron-spectroscopies"],"_links":{"self":[{"href":"https:\/\/equipes.lps.u-psud.fr\/puls\/wp-json\/wp\/v2\/posts\/4398","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/equipes.lps.u-psud.fr\/puls\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/equipes.lps.u-psud.fr\/puls\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/equipes.lps.u-psud.fr\/puls\/wp-json\/wp\/v2\/users\/23"}],"replies":[{"embeddable":true,"href":"https:\/\/equipes.lps.u-psud.fr\/puls\/wp-json\/wp\/v2\/comments?post=4398"}],"version-history":[{"count":1,"href":"https:\/\/equipes.lps.u-psud.fr\/puls\/wp-json\/wp\/v2\/posts\/4398\/revisions"}],"predecessor-version":[{"id":4400,"href":"https:\/\/equipes.lps.u-psud.fr\/puls\/wp-json\/wp\/v2\/posts\/4398\/revisions\/4400"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/equipes.lps.u-psud.fr\/puls\/wp-json\/wp\/v2\/media\/4399"}],"wp:attachment":[{"href":"https:\/\/equipes.lps.u-psud.fr\/puls\/wp-json\/wp\/v2\/media?parent=4398"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/equipes.lps.u-psud.fr\/puls\/wp-json\/wp\/v2\/categories?post=4398"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/equipes.lps.u-psud.fr\/puls\/wp-json\/wp\/v2\/tags?post=4398"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}