Probing magnetic Dynamics inNanoarrays using AC susceptibility

Sammanfattning: This project revised a magneto-optical ac susceptometer aiming to improve the experimentalapproach to investigate the magnetization dynamics of magnetic nano arrays.First the experimental setp was equipped with a new Helmholtzcoil which enables strongerAC magnetic eld compared to the installed coils on the system. That includes i.e. higherRMS magnetic eld amplitudes and a higher cut-o frequency in order to increase thefrequency range for magnetization dynamic measurements. Therefore dierent coil prototypeswere fabricated and tested in table top experiments using dierent additive manufacturingmethods, before the coil was installed on the cryostat and calibrated in thesoftware.In the second part of the project magnetization dynamics of nanostructures were studiedwith this new setup. As a rst step the general functionality of the Set-Up was testedusing a continuous ferromagnetic lm. Subsequently patterned circular discs were investigatedaiming to improve the calibration of the newly designed Helmholtzcoil. Startingfrom pattern with non coupled elements the project lastly investigated frequency dependentthermally active square articial spin ice (sASI), measuring freezing dynamics usingthe frequency dependent AC susceptometer.