Regensburg 2022 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 31: Superconducting Electronics and Cryogenics: Poster Session
TT 31.18: Poster
Donnerstag, 8. September 2022, 15:00–18:00, P1
Quantum electrodynamics of cold deposited granular aluminum — •Ameya Nambisan1, Dennis Rieger2, Simon Günzler1, Wolfgang Wernsdorfer1,2,3, and Ioan M Pop1,2 — 1Institute for Quantum Materials and Technology (IQMT), Karlsruhe Institute of Technology (KIT), Germany — 2Physikalisches Institut (PHI), Karlsruhe Institute of Technology (KIT), Germany — 3Institute Néel, CNRS Grenoble, France
In recent times, superconducting granular aluminium (grAl) has found increasing interest in the superconducting quantum circuits community because of its promising characteristics such as its tunable kinetic inductance, low microwave losses, high in-plane critical magnetic field, and a higher critical temperature compared with pure Al.
In general, the critical temperature of a grAl film depends on its resistivity until it reaches a superconducting-to-insulator transition. For samples evaporated at room temperature, a maximum of around 2.2K is reached for resistivity of about 1000 µΩ. The critical temperature rises even above 3K when grAl is deposited on a substrate held at a lower temperature of 100K.
This project aims to answer the question of increased Tc, which is yet to be understood microscopically, and other consequences of cold deposition, such as how a generally smaller – while more homogeneous – grain size positively affects the electrodynamics of the film. The test-bed used to characterise the electrodynamics are stripline resonators fabricated entirely from cold-deposited grAl, and measured in a cylindrical copper waveguide sample holder at cryogenic temperatures.