Effects of magnetic field, strain, and size on the Morin temperature of spherical α-Fe2O3particles

New studies of the effects of the magnetic field, strain, and size on the Morin temperature, TM, of spherical α-Fe2O3particles of narrow size distribution with the mean diameters varying between 30 to 320 nm have been made using a vibrating sample magnetometer. Our particle data have been compared, using certain approximations, with the data from earlier single crystal studies. Possible role of defects on the observed magnetic behavior of small and/or strained α-Fe2O3particles is emphasized.