Observation of the superconducting proximity effect from surface states in SmB$_6$/YB$_6$ thin film heterostructures via terahertz spectroscopy
| Autor: | Stensberg, Jonathan, Han, Xingyue, Lee, Seunghun, McGill, Stephen A., Paglione, Johnpierre, Takeuchi, Ichiro, Kane, Charles L., Wu, Liang |
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| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | Phys. Rev. Lett. 130, 096901 (2023) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevLett.130.096901 |
| Popis: | The AC conduction of epitaxially-grown SmB$_6$ thin films and superconducting heterostructures of SmB$_6$/YB$_6$ are investigated via time domain terahertz spectroscopy. A two-channel model of thickness-dependent bulk states and thickness-independent surface states accurately describes the measured conductance of bare SmB$_6$ thin films, demonstrating the presence of surface states in SmB$_6$. While the observed reductions in the simultaneously-measured superconducting gap, transition temperature, and superfluid density of SmB$_6$/YB$_6$ heterostructures relative to bare YB$_6$ indicate the penetration of proximity-induced superconductivity into the SmB$_6$ overlayer; the corresponding SmB$_6$-thickness independence between different heterostructures indicates that the induced superconductivity is predominantly confined to the interface surface state of the SmB$_6$. This study demonstrates the ability of terahertz spectroscopy to probe proximity-induced superconductivity at an interface buried within a heterostructure, and our results show that SmB$_6$ behaves as a predominantly insulating bulk surrounded by conducting surface states in both the normal and induced-superconducting states in both terahertz and DC responses, which is consistent with the topological Kondo insulator picture. Comment: 7 pages, 3 figures. Accepted to Phys. Rev. Lett |
| Databáze: | arXiv |
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