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Please use this identifier to cite or link to this item: http://acervodigital.unesp.br/handle/11449/32293
Title: 
Spin reversal and magnetization jumps in ErMexMn1-xO3 perovskites (Me = Ni, Co)
Author(s): 
Institution: 
  • Univ Rennes 1
  • Ctr Univ FEEVALE
  • Universidade Federal do Rio Grande do Sul (UFRGS)
  • Universidade Estadual Paulista (UNESP)
  • CSIC
ISSN: 
0304-8853
Abstract: 
The erbium-based manganite ErMnO3 has been partially substituted at the manganese site by the transition-metal elements Ni and Co. The perovskite orthorhombic structure is found from x(Ni) = 0.2-0.5 in the nickel-based solid solution ErNixMn1-xO3, while it can be extended up to x(Co) = 0.7 in the case of cobalt, provided that the synthesis is performed under oxygenation conditions to favor the presence of Co3+. Presence of different magnetic entities (i.e., Er3+, Ni2+, Co2+, Co3+, Mn3+, and Mn4+) leads to quite unusual magnetic properties, characterized by the coexistence of antiferromagnetic and ferromagnetic interactions. In ErNixMn1-xO3, a critical concentration x(crit)(Ni) = 1/3 separates two regimes: spin-canted AF interactions predominate at x < x(crit), while the ferromagnetic behavior is enhanced for x > x(crit). Spin reversal phenomena are present both in the nickel- and cobalt-based compounds. A phenomenological model based on two interacting sublattices, coupled by an antiferromagnetic exchange interaction, explains the inversion of the overall magnetic moment at low temperatures. In this model, the ferromagnetic transition-metal lattice, which orders at T-c, creates a strong local field at the erbium site, polarizing the Er moments in a direction opposite to the applied field. At low temperatures, when the contribution of the paramagnetic erbium sublattice, which varies as T-1, gets larger than the ferromagnetic contribution, the total magnetic moment changes its sign, leading to an overall ferrimagnetic state. The half-substituted compound ErCo0.50Mn0.50O3 was studied in detail, since the magnetization loops present two well-identified anomalies: an intersection of the magnetization branches at low fields, and magnetization jumps at high fields. The influence of the oxidizing conditions was studied in other compositions close to the 50/50 = Mn/Co substitution rate. These anomalies are clearly connected to the spin inversion phenomena and to the simultaneous presence of Co2+ and Co3+ magnetic moments. Dynamical aspects should be considered to well identify the high-field anomaly, since it depends on the magnetic field sweep rate. (C) 2006 Elsevier B.V. All rights reserved.
Issue Date: 
1-May-2007
Citation: 
Journal of Magnetism and Magnetic Materials. Amsterdam: Elsevier B.V., v. 312, n. 1, p. 78-90, 2007.
Time Duration: 
78-90
Publisher: 
Elsevier B.V.
Keywords: 
  • spin reversal
  • magnetic oxide
  • magnetization jump
  • magnetic exchange
Source: 
http://dx.doi.org/10.1016/j.jmmm.2006.09.012
URI: 
Access Rights: 
Acesso restrito
Type: 
outro
Source:
http://repositorio.unesp.br/handle/11449/32293
Appears in Collections:Artigos, TCCs, Teses e Dissertações da Unesp

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