Author(s): Daniel Halliday, Izidor Benedičič, Andela Zivanovic, Masahiro Naritsuka, Brendan Edwards, Tommaso Antonelli, Naoki Kikugawa, Dmitry A. Sokolov, Craig Polley, Andrew P. Mackenzie, Georg Held, Phil D. C. King, and Peter Wahl We investigate the electronic structure at the surface of the correlated oxide ${\mathrm{Ca}}_{3}{\mathrm{Ru}}_{2}{\mathrm{O}}_{7}$, a low-symmetry ruthenate oxide which hosts an unconventional polar-metal phase. From a combination of angle-resolved photoemission spectroscopy and scanning tunneling … [Phys. Rev. Lett. 137, 096503] Published Wed Aug 26, 2026