Anomalous metallic states and Majorana zero modes in 2D crystalline superconductors

After decades of explorations, suffering from the subtle nature, whether a metallic ground state exists in a two-dimensional (2D) superconducting system is still a mystery. In high-Tc superconducting films with patterned nanopores, a robust intervening anomalous metallic state characterized by both resistance and oscillation amplitude saturations in the low temperature regime is detected, which suggests the formation of the anomalous metallic state (i.e. quantum metal or Bose metal). [1] The anomalous metallic state is further detected in the macro-size ambient-stable ultrathin crystalline PdTe2 films grown by molecular beam epitaxy. [2] As for 2D crystalline transition metal dichalcogenide superconducting devices, our work indicates that at ultralow temperatures the anomalous metallic ground state can be experimentally revealed by using high-attenuation low-pass filters although at higher temperatures the metallic state induced by the external noise is observed.[3] Our findings offer the reliable evidences on the existence of anomalous quantum metallic ground states in 2D superconducting systems and shed light on the origin of anomalous metallic states.References:1. Science 366, 1505 (2019) accompanied with a perspective paper Science 366, 1450 (2019)1.2. Nano Lett. 20, 5728 (2020) highlighted by Editors' Choice Science 369, 388 (2020) 3. arXiv:2007.10843