Supercurrent as a probe for topological superconductivity in magnetic adatom chains

Abstract

A magnetic adatom chain, proximity coupled to a conventional superconductor with spin-orbit coupling, exhibits locally an odd-parity, spin-triplet pairing amplitude. We show that the singlettriplet junction, thus formed, leads to a net spin accumulation in the near vicinity of the chain. The accumulated spins are polarized along the direction of the local d-vector for triplet pairing and generate an enhanced persistent current flowing around the chain. The spin polarization and the "supercurrent" reverse their directions beyond a critical exchange coupling strength at which the singlet superconducting order changes its sign on the chain. The current is strongly enhanced in the topological superconducting regime where Majorana bound states appear at the chain ends. The current and the spin profile offer alternative routes to characterize the topological superconducting state in adatom chains and islands.

Transport in two-dimensional topological materials: recent developments in experiment and theory

“…More recent theories have revisited the fractional JE in the context of MZMs in hybrid structures combining conventional superconductors with topological insulators or semiconductor nanowires [440,448,494,495,496,497,498,499,500,501,502,503,504,505,506,507,455,508,509,510,457,511,512,513,514,515,516,517,518,519,520,521,522,523,524]. Theoretically, the 4π -periodic CPR (69) has been proposed for ferromagnetic weak links in quantum spin-Hall insulator/superconductor structures under assumption of the local fermion-parity conservation [440].…”

Skyrmion Control of Majorana States in Planar Josephson Junctions

“…The broken inversion symmetry at the interface between the 2DEG and the superconductor, often leads to a sizable intrinsic Rashba SOC which is usually considered as the primary mechanism for modifying the pairing symmetry of the induced superconductivity 50,51 , leading to the desired topological superconductivity. We find that the MBS remain robust in the presence of the intrinsic Rashba SOC (see Supplementary Information).…”

Bound States Induced by the Ferromagnetic Dimer in a Triangular Lattice

“…Indeed, after the second crossing P increases again by 1/2, reaching the value of 1. In fact in a general case, number of the QPTs in the system depends on the number of the adatoms [34,35]. Each crossing at the Fermi level corresponds to reduction of the value of the order parameter.…”