Low temperature ion bombardment combined with in-situ ac-susceptibility measurements

As has been demonstrated previously, ion bombardment of magnetic films at optimized temperatures allows fine tuning of various magnetic properties like Curie-temperature, hysteretic behavior, exchange bias fields as well as magnetically relevant structural phase transitions. In many cases, it is desirable to find a relation between certain types of defects or of disorder and corresponding changes of a specific magnetic property. For this purpose, a new low temperature (T>6 K) ac-susceptometer was developed and combined with the beam-line of a 300 keV ion accelerator. The design of this system will be introduced and its performance demonstrated by first measurements on FePt films and nanoparticles