High temperature magnetic insulating phase in ultrathin La0.67Sr0.33MnO3   films
  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. 
Hans Boschker, Jaap Kautz, Evert P. Houwman, Wolter Siemons, Mark   Huijben, Dave H.A. Blank, Gertjan Koster, Arturas Vailio...
cond-mat.mtrl-sci cond-mat.str-el