Booth, Kevin2020-02-262020-02-262019-12https://hdl.handle.net/11299/211715University of Minnesota M.S. thesis. December 2019. Major: Physics. Advisor: Earl Dahlberg. 1 computer file (PDF); iv, 19 pages.The differential ac magnetic susceptibility of thin magnetic films was determined using the anisotropic magnetoresistance (AMR) to measure the response of the magnetization to an applied ac magnetic field. The ac susceptibility was measured as a function of an applied dc magnetic field. The frequency of the applied ac field was varied between 5Hz to 5000Hz. The ferromagnetic films investigated were permalloy, cobalt, nickel, and nickel with an antiferromagnetic nickel oxide layer on one surface. For all the samples investigated, the differential susceptibility magnitude was a function of the dc field magnitude and was frequency dependent, decreasing with increasing frequency.enAC SusceptibilityAnisotropic MagnetoresistanceMagneticsThin FilmsThesis or Dissertation