Observation of flux-grown α-Fe₂O₃ single crystal at the morin transition by ⁵⁷Fe synchrotron radiation mössbauer diffraction

The Morin transition of a high-quality flux-grown single crystal of α-Fe₂O₃ was studied by ⁵⁷Fe synchrotron radiation Mössbauer diffraction. The measured rocking curves and Mössbauer spectra gave direct evidence that the coexistence of magnetic phases during the Morin transition occurred over a wide temperature range. The complex magnetic structure at the phase coexistence induced a large magnetostrictive distortion in the α-Fe₂O₃ crystal surface. In contrast, however, when the antiferromagnetic phase was dominant at low temperatures, the distortion disappeared, and the initial high crystal perfection was recovered. The spectral line shapes were discussed in terms of the interference between electronic and nuclear scatterings.