T. Fujii et al., SPIN-FLIP ANOMALIES IN EPITAXIAL ALPHA-FE2O3 FILMS BY MOSSBAUER-SPECTROSCOPY, Journal of magnetism and magnetic materials, 135(2), 1994, pp. 231-236
The spin-flip transition of 1000 angstrom-thick alpha-Fe2O3 films was
investigated by conversion electron Mossbauer spectroscopy from 2.5 to
673 K. The films were epitaxially formed on alpha-Al2O3 single-crysta
lline substrates by a reactive vapor deposition method. Not only the t
ransition temperature but also the spin axis were found to strongly de
pend upon the film orientation, probably as a result of anisotropic la
ttice strains caused by interactions with the substrate. For a (102)-o
riented film the transition takes place at about 400 K, much higher th
an the Morin transition temperature (260 K) of the free crystal, and t
he spin axis lying within the (102) plane above 400 K changes almost n
ormal to the plane at room temperature and below: the normal makes 57.
6-degrees with the spin axis of the free crystal. A (001)-oriented fil
m, on the other hand, does not show any transition at least down to 2.
5 K.