Volume 103, Number 2, July 2013
|Number of page(s)||6|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||14 August 2013|
Strain control of Morin temperature in epitaxial α-Fe2O3(0001) film
1 Department of Physics, Pohang University of Science and Technology - Pohang 790-784, Korea
2 Pohang Acceleration Laboratory, Pohang University of Science and Technology - Pohang 790-784, Korea
3 Division of Advanced Materials Science, Pohang University of Science and Technology - Pohang 790-784, Korea
Received: 21 May 2013
Accepted: 21 July 2013
We present comprehensive studies of strain effects on the spin reorientation transition (SRT), the so-called Morin transition, in α-Fe2O3(0001) films. The α-Fe2O3(0001) epitaxial films were grown with a Cr2O3 buffer layer on Al2O3(0001) substrates through an oxide molecular beam epitaxy. The antiferromagnetic spin axis was monitored by using the Fe L2-edge X-ray magnetic linear dichroism. The buffer layer was found to introduce compressive strain into the α-Fe2O3(0001) film due to its 1.6% smaller in-plane lattice constant. The degree of strain is monotonically reduced with the increase of the α-Fe2O3 film thickness and becomes relaxed in the thick region (> 20 nm). The transition temperature TM, which increases up to ≃360 K, well above the bulk TM = 263 K, for the film thickness ≃3 nm, gradually decreases as the film thickness increases. We also examined the Néel temperature TN in the ultra-thin region (< 3 nm), which rapidly drops with the decrease of the film thickness. The correlation between TM and the strain in the α-Fe2O3(0001) epitaxial films was found to be well explained in terms of two competing energies of magnetic dipole anisotropy and single-ion magnetocrystalline anisotropy except for the ultra-thin region, in which TN is dominated by the finite-size effects.
PACS: 75.50.Ee – Antiferromagnetics / 78.70.Dm – X-ray absorption spectra / 75.70.Ak – Magnetic properties of monolayers and thin films
© EPLA, 2013
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