Hans Boschker, Jaap Kautz, Evert P. Houwman, Wolter Siemons, Mark Huijben, Dave H. A. Blank, Gertjan Koster, Arturas Vailionis, Guus Rijnders
We present a study of the thickness dependence of magnetism and electrical conductivity in ultra thin La0.67Sr0.33MnO3 films grown on SrTiO3 (110) substrates. We found a critical thickness of 10 unit cells below which the conductivity of the films disappeared and simultaneously the Curie temperature (TC) increased, indicating a magnetic insulating phase at room temperature. These samples have a TC of about 560 K with a significant saturation magnetization of 1.2 +- 0.2 muB/Mn. The canted antiferromagnetic insulating phase in ultra thin films of n< 10 coincides with the occurrence of a higher symmetry structural phase with a different oxygen octahedra rotation pattern. Such a strain engineered phase is an interesting candidate for an insulating tunneling barrier in room temperature spin polarized tunneling devices.
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http://arxiv.org/abs/1210.4435
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