Superconducting diode effects in chiral topological semimetal

In a superconducting system, when a current bias is applied the system will carry current without dissipation up to a threshold current where the state switches to a normal metal with a finite resistance. In superconducting systems with broken inversion and time-reversal symmetries, the switching currents for positive and negative current bias can differ in magnitude leading to a superconducting diode effect (SDE). In this talk, we will present our study of the zero-magnetic-field SDE in superconducting chiral topological semimetal thin films. Using a combination of microscopic and phenomenological modeling, we investigate zero field SDE and the role of the phase coupling between the bulk and surface superconducting states in topological semimetals, which is known to break time-reversal symmetry and induce zero field SDE in Dirac semimetal Cd₃As₂ asymmetric devices. We find that interband Josephson coupling in a multiband superconductor with broken inversion symmetry can lead to a zero field SDE, which may be relevant to capture zero field SDE observed in superconducting CoSi thin films. We also discuss the role of possible magnetic order in CoSi affecting the SDE.