logo

| Date | Monday, February 10th, 2025

| Time | 10:00~

| Venue | 33동 222호(DB 세미나실)

Dimensional crossovers lead to pervasive phase transitions in nature, and exploring how reduced dimensionality intrigues the transformation of the fundamentals of physics has been a topic of great interest for decades. As a physical system becomes less dimensional, bulk effects wane, thereby making surface effects more dominant. However, transition of predominancy between these effects poses a challenge because conventional wisdom considers a Hamiltonian from surface effects as only a perturbation of bulk effects. In this study, we experimentally observe a colossal magnetic Rashba effect in atomically thin quasi-two-dimensional ferromagnetic materials, surpassing the established threshold for perturbative energy levels, even exceeding 100%. Our experimental investigations into anisotropic exchange interactions and orbital-moments asphericity uncover novel aspects of low-dimensional physics. Theoretical supports are provided by validating a non-local interaction model and tight-binding calculation, employing distinct pairing schemes for each exchange interaction throughout the dimensional crossover. Our discoveries highlight the novel aspects of fundamental physics in low-dimensional materials, elucidating the intricate effect of dimensionality on magnetic materials.