My relationship with rare earths started slightly before my Diploma (master) project in 2005. My task was to assemble and test an older UHV chamber for Spot-Profile -Analysis Low Enegry Electron Diffraction (SPA-LEED), of course not alone but with guidance of a PostDoc and Professor who had recently joined the University and who taught me lot (Thank you Carsten and Joachim!). To test the instrument we evaporated praseodymium oxide onto a piece of silicon wafer and studied the resulting structures with SPA-LEED and Auger electron spectroscopy. This choice of material was not completely random and the study developed into my Diploma thesis that I finished in 2006.
More on that and why that material was chosen soon...
Again, stay tuned. (Feb. 2026...20 years later)