Unveiling the anisotropic superconductivity and charge density wave order in 2D multiband superconductors with momentum-specific tunneling probe

Understanding how individual bands of the Fermi surface interact and contribute to the emergent properties of quantum materials—such as multigap superconductivity and charge density waves—remains a significant challenge, both experimentally and theoretically. A major limitation arises from the scarcity of experimental techniques capable of probing such complex electronic structures with both high energy and momentum resolution. Here, we introduce a momentum-resolved (q-resolved) electron tunneling spectroscopy approach based on planar van der Waals (vdW) tunneling junctions. This metrology offers a powerful platform for investigating the electronic structure of quantum materials with ultrahigh energy resolution, while simultaneously enabling the spectroscopic probing of electronic states at well-defined regions of momentum space. We demonstrate its capabilities on the prototypical two-dimensional superconductor NbSe₂, revealing direct signatures of momentum-dependent superconducting gaps and uncovering spectral features associated with the charge density wave transition—signals that have previously eluded detection in tunneling experiments. This methodology is broadly applicable to a wide class of low-dimensional systems, opening new opportunities for the study of quantum materials and providing a valuable addition to the experimental toolkit of modern Fermiology.