SKM 2023 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 30: Complex Oxides
TT 30.1: Vortrag
Mittwoch, 29. März 2023, 09:30–09:45, HSZ 204
Planar superconducting resonators on SrTiO3 and KTaO3: GHz properties of quantum paraelectrics — Vincent T. Engl, Nikolaj G. Ebensperger, Lars Wendel, Marius Tochtermann, Ilenia Neureuther, Ishan Sarvaiya, Cenk Beydeda, and •Marc Scheffler — 1. Physikalisches Institut, Universität Stuttgart, Stuttgart, Germany
SrTiO3 is a common substrate for perovskite thin films, and it hosts a superconducting interface when covered with LaAlO3. Recently, similar superconducting interfaces based on KTaO3 were realized. Any cryogenic electronics application using SrTiO3 or KTaO3 faces the quantum-paraelectric nature of both materials: upon cooling to temperatures of a few K, their very large real part є1 of the dielectric function complicates high-frequency device design, while the imaginary part є2 indicates rather high losses for SrTiO3 at GHz frequencies.
Overcoming the challenges of the high є1, we present coplanar superconducting Nb microwave resonators on SrTiO3 and KTaO3 substrates, which we operate at temperatures down to 25 mK. For SrTiO3 with є1 ≈ 20000 at low temperatures, we couple the coplanar resonator to a conventional 50 Ω feedline using a distant-flip-chip geometry.[1,2] With loaded quality factors exceeding 800 for SrTiO3 and 8000 for KTaO3 we advance the prospects of these quantum paraelectrics towards applications in oxide-based superconducting quantum circuitry.
[1] L. Wendel et al., Rev. Sci. Instrum. 91, 054702 (2020)
[2] V. T. Engl et al., arXiv:1911.11456 [cond-mat.supr-con]