Leonardo I. Escandon Jackson.
Magnetometer Measurements on large samples for magneto-plastic research.
Leo I. Escandon Jackson
Texas State University at San Marcos, Department of Physics, RFM 3228, 601 University Drive, San Marcos, TX78666.
Understanding the influence of stress and strain on the magnetic properties of thin films is important if one wants to apply magnetic films in devices such as recording heads, sensors, and actuators. Thin film magnetic properties can be determined by measuring the magnetic moment as a function of the magnetic field. A Vibrating Sample Magnetometer (VSM) measures the magnetic moment of a sample by vibrating it in between pickup coils where a field is applied by a water-cooled electromagnet; the voltage induced in the coils is proportional to the sample’s magnetization. To investigate the effect of stretching, the sample’s magnetic properties are measured before and after stretching the sample in an Instron materials tester. VSMs normally require small samples (1x1 cm2), but to stretch the sample in a materials tester the sample needs to be much larger (>5 cm). Large Nitinol substrates (2.5x7.5 cm2) were partially plated with a thin layer of Fe-Si (3%) by sputtering through a deposition mask. To handle such large samples in the VSM, a special sample holder was constructed consisting of a cut microscope slide and a clip rather than a screw connection. This approach allows the sample to be measured in the VSM before and after stretching it in the materials tester. The samples were mounted with rubber cement to the slide and the background of the new sample holder was smaller than 10-4 emu. Preliminary measurements show that reproducible hysteresis curves can be measured with the new sample holder.
Publications and Presentations:
 Leonardo I. Escandon Jackson, Yubo Cui, Wilhelmus Geerts, Magnetometer measurements on large samples for magneto-plastic research, Undergraduate Research Conference and Honors Thesis Forum, Texas State University April 24, 2015.