High-Temperature Magnetic Insulating Phase in Ultrathin ${\mathrm{La}}_{0.67}{\mathrm{Sr}}_{0.33}{\mathrm{MnO}}_{3}$ Films

High-Temperature Magnetic Insulating Phase in Ultrathin ${La}_{0.67} {Sr}_{0.33} {MnO}_{3}$ Films

Hans Boschker, Jaap Kautz, Evert P. Houwman, Wolter Siemons, Dave H. A. Blank, Mark Huijben, Gertjan Koster, Arturas Vailionis, and Guus Rijnders

Phys. Rev. Lett. 109, 157207 – Published 12 October 2012

Abstract

We present a study of the thickness dependence of magnetism and electrical conductivity in ultrathin ${La}_{0.67} {Sr}_{0.33} {MnO}_{3}$ films grown on ${SrTiO}_{3}$ (110) substrates. We found a critical thickness of 10 unit cells below which the conductivity of the films disappeared and simultaneously the Curie temperature increased, indicating a magnetic insulating phase at room temperature. These samples have a Curie temperature of about 560 K with a significant saturation magnetization of $1.2 \pm 0.2 μ_{B} / Mn$ . 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.

Received 2 August 2011

DOI:https://doi.org/10.1103/PhysRevLett.109.157207

Authors & Affiliations

Hans Boschker¹, Jaap Kautz¹, Evert P. Houwman¹, Wolter Siemons², Dave H. A. Blank¹, Mark Huijben¹, Gertjan Koster^1,*, Arturas Vailionis³, and Guus Rijnders¹

¹Faculty of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente, 7500 AE Enschede, The Netherlands
²Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
³Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA