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TT: Fachverband Tiefe Temperaturen

TT 11: Superconductivity: Poster

TT 11.8: Poster

Montag, 17. März 2025, 15:00–18:00, P4

Structural properties of YBa₂Cu₃O₇ thin film nanopatterns generated by focused He-ion-beam irradiation — •Robin Hutt¹, Cesar Magen², Christoph Schmid¹, Jan Ullmann¹, Simon Koch¹, Javier Pablo-Navarro², Ross Carter¹, Paul Zimmermann¹, Frank Schreiber¹, Dieter Koelle¹, Reinhold Kleiner¹, Ivan Zaluzhnyy¹, and Edward Goldobin¹ — ¹Universität Tübingen, Germany — ²INMA, Universidad de Zaragoza - CSIC, Spain

Irradiation of a YBa₂Cu₃O₇ (YBCO) thin film with a focused He ion beam (He-FIB) with spot size 10 nm changes its properties on the nanoscale. A moderate irradiation dose D supresses the critical temperature T_c locally, thus allowing us to “draw”, e.g., Josephson barriers, while a high D destroys (amorphizes) the crystal locally, letting us create highly resistive walls (edges of devices and holes) in one fabrication run. We report on the irradiation of YBCO thin films by He-FIB using single lines and rectangular areas with different doses and investigate the result using transmission electron microscopy (TEM). We visualize the crossover to amorphization at the critical dose D_c and the growth of the amorphous track width with D. Using a simple model, we obtain the value of D_c and FIB spot size with a good accuracy. In the areas irradiated by D<D_c we use strain analysis of the TEM images to detect subtle changes in the crystal structure. This is complemented by spatially-resolved X-ray diffraction data that indicate the swelling of the film in c-direction in irradiated regions. Finally, these observations are correlated with electric transport properties of irradiated areas.

Keywords: YBCO; He FIB; XRD; TEM