Magnetocrystalline anisotropy is found in many magnetic materials which means that the energy of a magnet depends on the magnetization direction. This keeps our windshield wipers moving and our toy magnets attached to the fridge. However, on changing the direction of the field that aligns the magnetic moments, the aligned magnetization normally remains nearly unchanged. A strikingly different behavior has been found by researchers at the University of Nebraska MRSEC.
Anisotropic magnetoresistance (AMR) is the difference in the resistivity of ferromagnetic materials in external magnetic field when the field is applied along or perpendicular to the current. In macroscopic materials the conductance is diffusive (the mean free path of the electron is much smaller than the device dimensions) and AMR is due to spin dependent scattering of impurities. Until recently AMR used to be the primary way of detecting magnetic fields (as in hard-drive read heads).
Art Institute of Chicago - Northwestern University Program in Conservation Science*
Professor Katherine Faber, Northwestern Liaison
Dr. Francesca Casadio, Mellon Conservation Scientist
Art Institute of Chicago - Northwestern University Program in Conservation Science*
Professor Katherine Faber, Northwestern Liaison
Dr. Francesca Casadio, Mellon Conservation Scientist