Anomalous Magnetic Moments As Evidence Of Chiral Superconductivity In A Bi/Ni Bilayer

There have been continuous efforts in searching for unconventional superconductivity in the past five decades. Compared to the well-established d-wave superconductivity in cuprates, the existence of superconductivity with pairing symmetries of other high angular momentum is less conclusive. Bi/Ni epitaxial bilayer is a potential unconventional superconductor with broken time reversal symmetry (TRS), for that it demonstrates superconductivity and ferromagnetism simultaneously at low temperatures. We employ a specially designed superconducting quantum interference device (SQUID) to detect, on the Bi/Ni bilayer, the orbital magnetic moments which are expected if the TRS is broken. An anomalous hysteretic magnetic response is indeed observed in the superconducting state, providing the evidence for the existence of chiral superconducting domains in the material.