Investigating Magnetic Anisotropy in Novel Materials Using Transverse Susceptibility
Natalie A. Frey Huls1, S. Sun2, C. Leighton3, A. Gupta4, H. Srikanth5,
Cindi L. Dennis1, and Robert D. Shull1
1Metallurgy Division, NIST, Gaithersburg, MD, 20899
2Department of Chemistry, Brown University, Providence, RI, 02912
3Department of Chemical Engineering and Materials, University of Minnesota,
Minneapolis, MN 55455
4MINT Center, University of Alabama, Tuscaloosa, AL, 35487
5Department of Physics, University of South Florida, Tampa, FL 33620
An understanding of the magnetic anisotropy, or the directional dependence of magnetic properties in materials is crucial to the research and development of a diverse range of applications ranging from thin films for magnetic recording to nanoparticles for MRI contrast enhancement and hyperthermia. Transverse susceptibility – the measurement of the magnetic susceptibility (the ratio of magnetization to applied field) in one direction as the external field is swept in a perpendicular direction – has been shown to be an excellent tool to directly probe the magnetic anisotropy and switching fields of a variety of materials. Here we present the transverse susceptibility measurement utilizing a highly sensitive self-resonant oscillator technique1 and demonstrate how this method can be used to gain important insight into the anisotropy and switching of several magnetic systems. Examples include tracking the temperature-dependent anisotropy field through the anomalous 120K magnetic transition in the complex oxide Pr0.5Sr0.5CoO32, investigating the thickness-dependent exchange coupling in ferromagnetic/antiferromagnetic epitaxial CrO2/Cr2O3 bilayer thin films3, and exploring competing inter- and intra-particle interactions in coupled Au-Fe3O4 nanoparticles. The implications for a frequency- and AC field-dependent measurement system are also discussed.
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