By combining ARPES with theoretical calculations, we reveal a dualistic band renormalization in La₄Ni₃O₁₀ relative to cuprates. At high energies, strong correlation induces waterfall-like renormalization in both systems, but at low energies, the characteristic kinks observed in cuprates are absent in La₄Ni₃O₁₀. This indicates negligible electron–phonon coupling, underscoring the central role of strong correlation in nickel oxide superconductivity.

We systematically studied the electronic structure of CsCr₃Sb₅ using ARPES and first-principles calculations. First-principles calculations show that CsCr₃Sb₅ retains the fundamental electronic structure characteristic of kagome materials. Compared with CsV₃Sb₅, the van Hove singularities and Dirac points are located farther from the Fermi level, while the flat band is situated closer to the Fermi level. The consistence between ARPES experiment and DMFT calculations suggest CsCr₃Sb₅ is a strongly correlated Hund metal with an incipient flat band near E_F.

We systematically investigated the electronic structure of Bi₄Br₄ using advanced sub-micrometer spatial- and spin-resolved ARPES. For the first time, we observed surface states with splitting characteristics on the (100) surface and directly detected a surface state gap. The experiments further revealed the spin-momentum locking nature of these (100) surface states, findings that are in excellent agreement with first-principles calculations. Additionally, the experiments revealed the presence of additional gapless electronic states within the gap of the (100) surface states, indicating the existence of one-dimensional topological hinge states in the system. These results provide compelling evidence for a higher-order topological insulating phase in Bi₄Br₄, establishing it as an ideal material platform for exploring the electronic properties and potential applications of one-dimensional boundary states.

Currently, most micro-ARPES and nano-ARPES systems with high spatial resolution are built based on synchrotron radiation. However, the significant loss of photon intensity upon focusing poses a major challenge for integrating micro-ARPES with spin-ARPES. Here, we developed the first laser-based ARPES system that simultaneously achieves sub-micrometer spatial resolution and high-efficiency spin detection. This system is expected to play a key role in cutting-edge research areas such as low-dimensional quantum materials, phase-separated materials, and in situ measurements of functional electronic devices.

Luttinger liquids were thought to exist only in (quasi-)1D systems. Here, we observe Luttinger liquid behavior in η-Mo₄O₁₁. Although the system appears quasi-2D, it is woven from three types of crossing 1D chains with orthogonal orbital characters, which enable weak interchain coupling and protect the Luttinger liquid phase. This discovery marks the first observation of such behavior in a higher-dimensional crystal and offers new insights into non-Fermi liquids in strongly correlated systems.