Transition-Edge Sensors (TESs) are extremely sensitive microcalorimeters, which take advantage of the sharpness of the superconducting transition. Use of proximity Mo/Au bilayers allows tuning critical temperature Tc. Study of superconducting proximity effect reveals a high quality interface and tracks the evolution of Tc with layers thicknesses. Nevertheless, the transition is hugely broadened by current, which can be interpreted as current-driven vortex-antivortex depairing. Both effects have impact on performances of TES-based radiation detectors, in development at the ICMAB.
Large current-induced broadening of the superconducting transition in Mo/Au transition edge sensors
Lourdes Fabrega, Agustin Camon, Carlos Pobes, Pavel Strichovanec, Raquel Gonzalez-Arrabal
Superconductor Science and Technology 32, 1, 015006, 2019
Figure: Cross-section TEM image of a Mo/Au bilayer deposited on a Si3N4 membrane; room temperature growth is required to prevent strains in the Mo layer and Si3N4 membrane. Columnar morphology is appreciated, as well as a flat, sharp Mo/Au interface, which results in very narrow superconducting transitions.