Tuning the onset of ferromagnetism in heterogeneous bimetallic nanoparticles by gas phase doping

Murtaza Bohra, Panagiotis Grammatikopoulos, Vidyadhar Singh, Junlei Zhao, Evropi Toulkeridou, Stephan Steinhauer, Joseph Kioseoglou, Jean-François Bobo, Kai Nordlund, Flyura Djurabekova, and Mukhles Sowwan
Phys. Rev. Materials 1, 066001 – Published 9 November 2017
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Abstract

In the nanoregime, chemical species can reorganize in ways not predicted by their equilibrium bulk behavior. Here, we engineer Ni-Cr nanoalloys at the magnetic end of their compositional range (i.e., 0–15 at. % Cr), and we investigate the effect of Cr incorporation on their structural stability and resultant magnetic ordering. To ensure their stoichiometric compositions, the nanoalloys are grown by cluster beam deposition, a method that allows one-step, chemical-free fabrication of bimetallic nanoparticles. While full Cr segregation toward nanoparticle surfaces is thermodynamically expected for low Cr concentrations, metastability occurs as the Cr dopant level increases in the form of residual Cr in the core region, yielding desirable magnetic properties in a compensatory manner. Using nudged elastic band calculations, residual Cr in the core is explained based on modifications in the local environment of individual Cr atoms. The resultant competition between ferromagnetic and antiferromagnetic ordering gives rise to a wide assortment of interesting phenomena, such as a cluster-glass ground state at very low temperatures and an increase in Curie temperature values. We emphasize the importance of obtaining the commonly elusive magnetic nanophase diagram for M-Cr (M=Fe, Co, and Ni) nanoalloys, and we propose an efficient single-parameter method of tuning the Curie temperature for various technological applications.

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  • Received 10 August 2017

DOI:https://doi.org/10.1103/PhysRevMaterials.1.066001

©2017 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied PhysicsInterdisciplinary Physics

Authors & Affiliations

Murtaza Bohra1,2, Panagiotis Grammatikopoulos1,*, Vidyadhar Singh1, Junlei Zhao3, Evropi Toulkeridou1, Stephan Steinhauer1, Joseph Kioseoglou4, Jean-François Bobo5, Kai Nordlund3, Flyura Djurabekova3, and Mukhles Sowwan1,*

  • 1Nanoparticles by Design Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha Onna-Son, Okinawa 904-0495, Japan
  • 2Mahindra Ecole Centrale, Survey Number 62/1A, Bahadurpally Jeedimetla, Hyderabad 500043, Telangana, India
  • 3Department of Physics and Helsinki Institute of Physics, University of Helsinki, P. O. Box 43, FIN-00014 Helsinki, Finland
  • 4Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece
  • 5Centre d'Elaboration de Materiaux et d'Etudes Structurales (CEMES), 29 rue Jeanne Marvig, 31055 Cedex 4 Toulouse, France

  • *Corresponding authors: pgrammatikopoulos@oist.jp; mukhles@oist.jp

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Issue

Vol. 1, Iss. 6 — November 2017

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