10.26165/JUELICH-DATA/XJICARJalil, Abdur RehmanAbdur RehmanJalilPGI-9 and JARA-FITSchmitt, Tobias, W.PGI-9 and JARA-FITRüßmann, PhilippPhilippRüßmannPGI-1 and University of WürzburgWei, Xian-KuiER-CFrohn, BenediktBenediktFrohnPGI-9 and JARA-FITSchleenvoigt, MichaelMichaelSchleenvoigtPGI-9 and JARA-FITWittl, WilhelmWilhelmWittlPGI-9Hou, XiaoXiaoHouJARA-FIT and GFE, RWTHSchmidt, AnneAnneSchmidtPGI-9 and JARA-FITUnderwood, KayceeKayceeUnderwoodPGI-9Bihlmayer, GustavGustavBihlmayerPGI-1Luysberg, MartinaMartinaLuysbergER-CMayer, JoachimJoachimMayerER-C and GFE, RWTHBlügel, StefanStefanBlügelPGI-1Grützmacher, DetlevDetlevGrützmacherPGI-9 and JARA-FITSchüffelgen, PeterPeterSchüffelgenPGI-9 and JARA-FITJülich DATA2024Physicstopological superconductivitysuperconductorsepitaxial interfacesinterface engineeringMajorana platformhybrid devicesJosephson junctionsTMDCtopological insulatorDFTRüßmann, PhilippPhilippRüßmannPGI-1 / IAS-12024-10-282024-10-2810.24435/materialscloud:w3-3c1.0CC0 WaiverProximity-induced superconductivity in hybrid devices of topological insulators and superconductors offers a promising platform for the pursuit of elusive topological superconductivity and its anticipated applications, such as fault-tolerant quantum computing. To study and harness such hybrid devices, a key challenge is the realization of highly functional material interfaces with a suitable superconductor featuring 2e-periodic parity-conserving transport to ensure a superconducting hard-gap free of unpaired electrons, which is important for Majorana physics. A superconductor well-known for this characteristic is Al, however, its direct integration into devices based on tetradymite topological insulators has so far been found to yield non-transparent interfaces. By focusing on Bi₂Te₃-Al heterostructures, this study identifies detrimental interdiffusion processes at the interface through atomically resolved structural and chemical analysis, and showcase their mitigation by leveraging different interlayers – namely Nb, Ti, Pd, and Pt – between Bi₂Te₃ and Al. Through structural transformation of the interlayer materials (X) into their respective tellurides (XTe₂) atomically-sharp epitaxial interfaces are engineered and further characterized in low-temperature transport experiments on Al-X-Bi₂Te₃-X-Al Josephson junctions and in complementary density functional theory calculations. By demonstrating functional interfaces between Bi₂Te₃ and Al, this work provides key insights and paves the way for the next generation of sophisticated topological devices.