Contents lists available at ScienceDirect Journal of Magnetism and Magnetic Materials journal homepage: www.elsevier.com/locate/jmmm Epitaxial stabilization of ordered Pd–Fe structures on perovskite substrates Renee M. Harton a , Vladimir A. Stoica b , Roy Clarke a a Department of Physics, University of Michigan, 450 Church St., Ann Arbor, MI 48109, USA b Department of Materials Science and Engineering, Pennsylvania State University, 201 Old Main, University Park, PA 16802, USA ARTICLE INFO Keywords: Epitaxy Ferromagnetism Perovskite Fe–Pd system ABSTRACT We report the fabrication of epitaxial ferromagnetic Pd 3 Fe thin films on SrTiO 3 (001) substrates by promoting the interdiffusion of an Fe/Pd multilayer heterostructure using thermal annealing. Prior to annealing, the results of in-situ Reflection High-Energy Electron Diffraction characterization suggest that each Fe and Pd layer exhibited an in-plane epitaxial relationship with the SrTiO 3 (001) substrate. X-Ray diffraction and magneto- optic Kerr effect characterization, conducted post-annealing, demonstrate that the film composition is majority Pd 3 Fe and exhibits in-plane magnetization reversal with a moderate coercive field of ≈760 Oe. This demonstration of an ordered atomic layer heterostructure grown on a perovskite substrate suggests a route to epitaxial interfacial structures which can achieve strain-assisted magnetic switching. 1. Introduction Thin film magnetic media have played a central role in the development of high capacity information storage technologies. Although this field has grown significantly since its infancy, the general requirements for a magnetic storage medium remain roughly the same, namely low power, high speed and high spatial resolution. For these systems, generally their operation rests on the ability to initialize, control, and maintain the magnetic states used to store information. Using epitaxial deposition methods, one is able to control the magne- tization as well as tune the properties of the thin film to ultimately optimize the performance of high-density recording media, [1–5]. Accordingly, the magnetic materials used for our study were thin films fabricated using ultra-high vacuum (UHV) deposition. In order to further promote low-power control of the magnetiza- tion, we use a material with coupled elastic and magnetic properties. The observation of pressure-induced invar behavior in Pd 3 Fe [6] suggested that such a coupling is enhanced in this material. For this reason, Pd 3 Fe was used as the magnetic material for thin film deposition. For the substrate material, we chose to use a member of the perovskite family of compounds on account of their good lattice match to transition metal layers [7], thus facilitating epitaxial film growth. In addition, the rich variety of structural phases that perovs- kites exhibit, especially piezoelectric and ferroelectric forms [8],offer interesting possibilities for substrate control of magnetism in epitaxial films. For example, several perovskite oxides, such as PZT [9] and BaTiO 3 [10], exhibit piezoelectric behavior within certain ranges of temperature, including ambient. Since the elastic properties of piezo- electric materials can be tuned using an externally applied voltage, these materials are useful as potential substrates for such heterostruc- tures. However, in order to enhance the coupling between the substrate and the deposited magnetic film, it was important that the film be epitaxial. Fabricating an epitaxial Pd 3 Fe film on a perovskite substrate is the focus of this report. In 2009, Wang et al. demonstrated the deposition of epitaxial Fe,Pd alloys onto SrTiO 3 (001) using co-deposition [11]. Although this method was successful for deposition onto this substrate, cubic in this case, the fabrication of an ordered film can be difficult on other perovskites where the lattice mismatch may not be as favorable, such as BaTiO 3 (001). The interdiffusion method provides some flexibility whereby the mismatch strain can be accommodated more gradually, as demonstrated in the work reported here. In this paper, we present a method to grow epitaxial ordered Pd 3 Fe films onthe perovskite SrTiO 3 (001) using the interdiffusion of an Fe/ Pd/SrTiO 3 (001) heterostructure. 1.1. Material and methods For this study, an Fe/Pd multilayer heterostructure was fabricated by depositing alternating layers of Fe and Pd onto a SrTiO 3 (001) substrate using vapor deposition in an ultra-high vacuum chamber (UHV deposition). The dimensions of the SrTiO 3 (001) substrate were 10 mm × 10 mm × 0.5 mm. Prior to loading in the chamber, the substrate was rinsed in boiling methanol. The excess liquid was http://dx.doi.org/10.1016/j.jmmm.2016.12.112 Received 9 September 2016; Received in revised form 21 December 2016; Accepted 22 December 2016 E-mail address: reneehar@umich.edu (R.M. Harton). Journal of Magnetism and Magnetic Materials 429 (2017) 29–33 Available online 27 December 2016 0304-8853/ © 2016 Published by Elsevier B.V. MARK