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Evidence of finite-size effect on the Néel temperature in ultrathin layers of CoO nanograins

M. Molina-Ruiz, A. F. Lopeandía, F. Pi, D. Givord, O. Bourgeois, and J. Rodríguez-Viejo
Phys. Rev. B 83, 140407(R) – Published 15 April 2011

Abstract

A significant reduction in the Néel temperature of CoO ultrathin films is revealed by highly sensitive specific heat measurement. It is found that the films consist of weakly coupled antiferromagnetic (AF) grains. The TN reduction from large to small grain samples scales with the grain size reduction, according to the Binder theory of critical phenomena in systems of reduced dimensions. In these finite AF nanosystems, the intergrain exchange interaction is reduced by the presence of surface Co spins, weakly coupled to Co moments inside the grains.

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  • Received 28 February 2011

DOI:https://doi.org/10.1103/PhysRevB.83.140407

©2011 American Physical Society

Authors & Affiliations

M. Molina-Ruiz1, A. F. Lopeandía1,2, F. Pi1, D. Givord2, O. Bourgeois2, and J. Rodríguez-Viejo1,3

  • 1Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
  • 2Institut Néel, CNRS et Université Joseph Fourier, 25 avenue des Martyrs, F-38042 Grenoble Cedex 9, France
  • 3MATGAS Research Centre, Campus UAB, 08193 Bellaterra, Spain

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Issue

Vol. 83, Iss. 14 — 1 April 2011

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