Magnetization Characterization Laboratory

Facilities

The Materials Science and Engineering Division has developed a Magnetics Laboratory with an unusually wide range of magnetic characterization tools and capabilities:

• SQUID, VSM, and VSM-SQUID magnetometry
• First order reversal curve (FORC) capability
• AC susceptometry
• B-H Looper
• Ferromagnetic resonance (FMR) spectrometry
• Mössbauer spectrometer
• Magnetic field calorimeter
• Kerr microscopy
• Magneto-optic imaging film (MOIF) apparatus
• Absolute Faraday balance magnetometry
• Field-free Lorentz electron microscopy

Significance

Commercial use of magnetic materials for motors, generators, transformers, information storage, MRI contrast agents, xerographic copiers, credit cards, etc., all depend on the specific magnetic characteristics of materials. For example, a magnet used in generators would certainly not be good for its use in a xerographic copier, or for magnetic data storage. Consequently, to properly characterize a magnetic material, one needs to measure a wide range of characteristics. Our laboratory has a whole host of measurement tools, enabling measurement of magnetization, superconducting transition temperatures, coercivity, magnetic anisotropy, spin freezing temperatures, magnetic entropies, domain nucleation fields, and magnetic state. This is unusual because most laboratories can measure only a few of these characteristics.

The MOIF domain imaging tool developed in this laboratory is shown on the right. It is unique in that one can image magnetic domains while they are forming, growing, and disappearing. Most domain imaging techniques do not have real time capabilities. As a consequence, this tool enables a visual study of magnetization dynamics while a magnetization reversal is occurring, information critical for understanding certain magnetic phenomena.