






RL2: Superconducting Materials for Emerging Technologies
This Research Line is devoted to deploy unique know-how in superconducting materials and their use in emerging areas of energy, efficient ICT, high energy physics and astrophysics. In particular, our effort is concentrated in three main aspects. Firstly, in developing high-throughput, low-cost growth methods for Coated Conductors (CC) with engineered properties to approach theoretical limits. Also, in investigating superconducting electronic functionalities based on controlling properties of cuprates for ICT and impelling ultrasensitive Transition Edge Sensors (TES) as single photon and phonon detectors. Finally, in customizing CC materials for adequate integration in large scale systems (energy and high energy physics).
Our breakthrough in the development of the Transient Liquid Assisted growth (TLAG) process of cuprates at 100-1000 nm/s growth rates is now fully exploited in the in-situ growth platform at ALBA synchrotron, including the analysis of compositional gradient samples also in collaboration with Kyushu University. Now we have extended the feasibility of this approach to films prepared by Pulsed Laser Deposition, additionally to Chemical Solution Deposition. Also, new emerging ideas were initiated for its use in superconducting joints also involving differentiated oxygenation studies to reach large vortex pinning in the overdoped state.
In the investigation of electronic functionalities, nonlinear optical signatures of quantum phase transitions in the high-temperature superconductor YBCO have been investigated through magneto-transport and high harmonic generation technologies. Manipulation of the superconducting order parameter and electromigration effects were explored in cuprate high-temperature superconductors. In addition, in the framework of the European CHIST-ERA project, on-chip magnetic metasurfaces with efficient control of magnetic fields have been explored for boosting the sensitivity and efficiency of magnetic sensors and functional devices
Besides, in 2023 we worked on electrothermal modelling and noise analysis of TES for X-ray detection, as well as on determining their transition mechanisms. Also, within a project aimed at developing TESs for low-mass dark matter direct detection we started optimization of W films with very low Tc, and worked on the understanding of the decay processes suffered by the created phonons prior to their detection by the TES.
Our scouting activities in customization of CC has led to identified the best architecture to increase the electrical grid protection against short circuits by using surface modified CC in superconducting devices. Additionally, our consolidated collaboration with CERN in the development of low surface impedance superconducting coatings has expanded to high gradient electric fields and high magnetic field studies for accelerators and dark matter search.

Telles, G.; Romanov, A.; Calatroni, S.; Granados, X.; Puig, T.; Gutierrez, J.Nature Communications 2023, 14, 6486.
https://doi.org/10.1088/1361-6668/ac97c9
RE(=Y, Gd, Eu)Ba2Cu3O7−x proposed as a low-surface impedance coating for the beam screen of a circular collider. Persistent currents in the superconductor will degrade the magnetic field homogeneity inside the beam chamber. We have explored the possibility of using a highly conductive hybrid coating made of Cu and REBa2Cu3O7−x. This decreases the surface impedance when compared to that of pure copper, while maintaining high magnetic field quality inside the beam screen chamber.

Queraltó, A.; Sieger, M.; Gupta, K.; Meledin, A.; Barusco, P.; Saltarelli, L.; de Palau, M.; Granados, X.; Obradors, X.; Puig, T.
https://doi.org/10.1088/1361-6668/acaad3
Investigation of the integration of transient liquid-assisted growth (TLAG) approach for epitaxial YBa2Cu3O7−x (YBCO) films by physical deposition methodologies. Highly flat and amorphous YBCO precursor films were deposited by PLD at temperatures below 400 °C on single-crystalline SrTiO3 (STO) and LaMnO3 (LMO)/STO.

Fourneau, E., Arregi, J. A., Barrera, A., Nguyen, N. D., Bending, S., Sanchez, A., Uhlíř, V., Palau, A., Silhanek, A. V.
https://doi.org/10.1002/admt.202300177
The effects of downscaling magnetic metamaterials for on-chip integration is investigated. The influence of the non-linear magnetic response of the ferromagnetic components, their magnetic irreversibility, the formation of magnetic domains, as well as the effects of geometry and size of the devices are scrutinized.

Barusco, P.; Giguere, J.; Lacroix, C.; Sirois, F.; Granados, X.; Puig, T.; Obradors, X.
https://doi.org/10.1088/1361-6668/ad01ec
The current flow diverter (CFD) is a known concept that has proven to effectively reduce the probability of destructive hot spots in REBa2Cu3O7 coated conductors (CCs) by boosting the normal zone propagation velocity. The implementation of this concept requires additional steps in a fabrication process that is already complex and has struggled to find a simple reel-to-reel fabrication method.