Realization of distinct phases in cuprate thin films through reactive molecular beam epitaxy

Cuprate superconductors, having the highest superconducting transition temperature under ambient pressure in the material family, has been a major focus in condensed matter physics since its discovery. While high-quality single crystals are usually helpful for investigating these materials, certain important phases in cuprates are hardly accessible with bulk synthesis methods. Using reactive oxide molecular beam epitaxy, we synthesized p-type infinite-layer AECuO₂ heterostructures and n-type T'-La_2-xCe_xCuO₄, which are generally not stable in bulk. The microscopic electronic structures were studied by performing in situ synchrotron-based angle-resolved photoemission spectroscopy. In the electron-doped case, a notable kink feature was observed across the entire fermi surface, and the momentum dependence of the kink energy reveals potential roles played by mutiple electron-phonon coupling modes within the system. Our results provide novel material platforms in studying high temperature superconductivity, which are essential for understanding the underlying mechanisms in the future.