  Anomalous resistance upturn and downturn have been observed on the
topological insulator (TI) surface in superconductor-TI (NbN-Bi1.95Sb0.05Se3)
heterostructures at ~ mm length scales away from the interface.
Magnetotransport measurements were performed to verify that the anomaly is
caused due to the superconducting transition of the NbN layer. The possibility
of long range superconducting proximity effect due to the spin-polarized TI
surface state was ruled out due to the observation of similar anomaly in NbN-Au
and NbN-Al heterostructures. It was discovered that the unusual resistance
jumps were caused due to current redistribution at the superconductor-TI
interface on account of the geometry effects. Results obtained from finite
element analysis using COMSOL package has validated the proposed current
redistribution (CRD) model of long range resistance anomalies in
superconductor-TI and superconductor-metal heterostructures.
