Site-Resolved Contributions to the Magnetic-Anisotropy Energy and Complex Spin Structure of Fe/MgO Sandwiches

Ramón Cuadrado, László Oroszlány, András Deák, Thomas A. Ostler, Andrea Meo, Roman V. Chepulskii, Dmytro Apalkov, Richard F. L. Evans, László Szunyogh, and Roy W. Chantrell
Phys. Rev. Applied 9, 054048 – Published 30 May 2018
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Abstract

Fe/MgO-based magnetic tunnel junctions are among the most promising candidates for spintronic devices due to their high thermal stability and high tunneling magnetoresistance. Despite its apparent simplicity, the nature of the interactions between the Fe and MgO layers leads to complex finite-size effects and temperature-dependent magnetic properties which must be carefully controlled for practical applications. In this article, we investigate the electronic, structural, and magnetic properties of MgO/Fe/MgO sandwiches using first-principles calculations and atomistic spin modeling based on a fully parametrized spin Hamiltonian. We find a large contribution to the effective interfacial magnetic anisotropy from the two-ion exchange energy. Minimization of the total energy using atomistic simulations shows a surprising spin-spiral ground-state structure at the interface owing to frustrated ferromagnetic and antiferromagnetic interactions, leading to a reduced Curie temperature and strong layerwise temperature dependence of the magnetization. The different temperature dependences of the interface and bulklike layers results in an unexpected nonmonotonic temperature variation of the effective magnetic-anisotropy energy and temperature-induced spin-reorientation transition to an in-plane magnetization at low temperatures. Our results demonstrate the intrinsic physical complexity of the pure Fe/MgO interface and the role of elevated temperatures providing insight when interpreting experimental data of nanoscale magnetic tunnel junctions.

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  • Received 4 December 2017
  • Revised 9 April 2018

DOI:https://doi.org/10.1103/PhysRevApplied.9.054048

© 2018 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Ramón Cuadrado1,2,3,*, László Oroszlány4, András Deák5, Thomas A. Ostler6,7, Andrea Meo1, Roman V. Chepulskii8, Dmytro Apalkov8, Richard F. L. Evans1, László Szunyogh5,9, and Roy W. Chantrell1

  • 1Department of Physics, University of York, York YO10 5DD, United Kingdom
  • 2Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
  • 3Universitat Autonoma de Barcelona, 08193 Bellaterra (Cerdanyola del Valles), Spain
  • 4Department of Physics of Complex Systems, Eötvös University, Pázmány Péter sétány 1/A, H-1117 Budapest, Hungary
  • 5Department of Theoretical Physics, Budapest University of Technology and Economics, Budafoki út 8, H-1111 Budapest, Hungary
  • 6Faculty of Arts, Computing, Engineering and Sciences, Sheffield Hallam University, Howard Street, Sheffield, S1 1WB, United Kingdom
  • 7Department of Physics, Université de Liège, B-4000 Liège, Belgium
  • 8Samsung Electronics, Semiconductor R and D Center (Grandis), San Jose, California 95134, USA
  • 9MTA-BME Condensed Matter Research Group, Budapest University of Technology and Economics, Budafoki út 8, H-1111 Budapest, Hungary

  • *ramon.cuadrado@icn2.cat

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Issue

Vol. 9, Iss. 5 — May 2018

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