Why do electrons and atoms in a solid state material spontaneously arrange themselves in patterns, and how does this relate to tunable electrical conduction?

Left: energy-momentum spectra along the Ta-chain direction in Ta2NiSe5

• Kang et al., Physical Review Materials 10, L053201 (2026), Editors' Suggestion

• Tang et al., Physical Review B 112, L201106 (2026), Editors' Suggestion

• Chen et al., Nature Communications 14, 7512 (2023), Focus in condensed matter

• Chen et al., Physical Review Research 5, 043089 (2023)

How can low dimensionality make materials switch between a metal, an insulator and a superconductor? Where does the energy go during these transitions? (How) can we make the system Tc higher? How do correlated orders interact with each other and (how) can we manipulate these orders?

Left: energy-momentum spectra along the nodal direction in Bi2Sr2CaCu2O8

• Yang et al, Proc. Natl. Acad. Sci. 123, e2536919123 (2026); Yale News

• Sous, He, Kivelson, npj Quantum Materials 8, 25 (2023)

• He et al., Phys. Rev. X 11, 031068 (2021)

How can the electronic properties of itinerant magnets be used to create high temperature magnetic materials in two-dimensions for real world spintronic applications?

Left: Fermi-surface measured within the van der Waals plane of Ni-doped Fe5GeTe2

• Werner et al., arXiv:2609.11862

• Li et al., Phys. Rev. Lett. 136, 216503 (2026), Editors' Suggestion, front cover, Yale News

Isoelectronic molecules often share similar chemical properties - can lab-designed solids be used to simulate the quantum properties in their isoelectronic and/or isostructural siblings?

Left: our newly commissioned portable organic molecular beam epitaxy system for versatile molecular self assembly. Inset: molecular beam epitaxy grown naphthalocyanine (H2Pc) monolayer of which structure mimics a 2D square lattice system and which may modify the electronic structure of the substrate.

https://arxiv.org/abs/2603.14446 (to appear, ACS Nano, front cover)

Traditional approach to conduct temperature dependent studies in ARPES involves global warm-cool cycles of the entire (massive) cryostat. This process is not only time-consuming and energy-inefficient, but more damagingly causes outgassing that is often detrimental to the fresh sample surface under active investigation. As shown to the left, a high-power CW laser is employed to achieve localized sample heating and create graduated thermal profiles on the sample surface. It will also be used to flash clean the surfaces of ex-situ prepared heterostructure devices and patterned structures. Moreover, it will be used to modify surface adsorbate density during and after targeted gas molecule or alkaline metal deposition. Last but not least, it can also maintain a steady state exciton population.

Integration of nanophotonics design with traditional ARPES substrate also offers another route towards more extreme sample environment, and will also path the way to a generic, compact, low cost, and highly controllable on-demand property tuning as well as the creation of new phases.

• magnetoARPES with magnetic meta material superlattice:

Li et al., J. Phys. Chem. Lett. 16, 12947 (2025), front cover, Yale News

• sub-resolution superconducting energy gap extraction: contact Xinhao Yang (xinhao.yang@yale.edu)

• automatic spectral feature extraction with machine learning

Chen et al., Newton 1, 10066 (2026)

• Turning ARPES into a thermodynamic probe via condensation energy analysis: contact Jinming Yang (jinming.yang@yale.edu)

• 4D X-Y-E-kp spectral information extraction (symmetry, mosaicity, intensity)

Eric Sun, https://ieeexplore.ieee.org/abstract/document/10002223

• Multi-BZ ARPES for wave function extraction

He et al., Advanced Materials Interfaces 12, 2400427 (2024)