Meissner screening of Proximity coupled Topological Insulator/Superconductor Heterostructures

Meissner screening of proximity coupled SmB₆/YB₆ topological insulator-superconductor (TI/SC) thin-film-bilayers is studied through the temperature dependence of the effective penetration depth. A microwave resonator technique is used in which the bilayers are exposed to the rf magnetic field. The study is conducted by systematically varying the thickness of the SmB₆ layer on top of the YB₆ layer. Unconventional thickness dependence of the temperature profile of the effective magnetic penetration depth of the TI/SC bilayer is observed, which is distinctly different from that of the conventional metal/superconductor bilayers. This provides evidence for Meissner screening in the presence of bulk insulating states in the SmB₆. Through an electromagnetic screening model, key parameters such as normal screening length, normal coherence length, thickness of the surface states, and Fermi velocity of SmB₆ are extracted and found to be in reasonable agreement with previous studies.