Pulse and low temperature magnetometry of /spl gamma/-Fe/sub 2/O/sub 3/ dispersions

Water and organic based dispersions of a /spl gamma/-Fe/sub 2/O/sub 3/ pigment have been prepared and measured using low temperature and pulsed field magnetometry. The objective of the study is to examine the role of dynamic effects in pulsed field measurements by comparison with low temperature studies where no such effects can occur. We find that fast pulsed fields t<100 /spl mu/s effectively freeze the dispersion and enable studies of magnetic properties to be made without affecting the microstructure. Additionally, remanence curves and hysteresis loops have been measured at low temperatures to determine changes to the microstructure of the dispersion brought about by milling. /spl delta/M plots showed an increase in negative interactions with milling time for the organic based dispersion but a decrease In these interactions for the water based dispersion.