Asymmetric Fraunhofer Patterns of Bi₂Se₃ Josephson Junctions

Josephson junctions with topological insulators as their weak link (S-TI-S junctions) are predicted to host Majorana fermions, which are key to creating qubits for topologically protected quantum computing. We fabricate a Bi₂Se₃ junction with NbTi leads and measure the Fraunhofer patterns of the junction in conjunction with applied in-plane fields, in order to observe the expected asymmetry and finite momentum shift effects. Asymmetric Fraunhofer patterns from the sample appear at zero parallel field and up to 1K, and appear in the maps of B_z vs. B_x,y, with aperiodic node spacings, suggesting they originate from the physical shape of the junction.