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The European Physical Journal B
ISSN: 1434-6028 (printed version)
ISSN: 1434-6036 (electronic version)
Abstract Volume 2 Issue 4 (1998) pp 469-474
Magnetic resonance in oxygen-doped La$\sf_2$NiO$\sf_{4+\delta}$
N.J. Poirot (1), P. Simon (1), P. Odier (1) (a), J.M. Bassat (2)
(1) Centre de Recherches sur la Physique des Hautes Températures, CNRS, 45071 Orléans Cedex 2, France
(2) ICMCB, CNRS, 33608 Pessac Cedex, France
Received: 3 November 1997 / Accepted: 23 December 1997
Abstract: We report an investigation of magnetic resonance by ESR in oxygen-doped La2NiO$_{4+\delta}$ emphasizing extensively for the first time the role of oxygen stoichiometry. The work is performed at room temperature and on powders with $0.015\leq \delta\leq 0.17$. At low field an hysteresis is detected between increasing and decreasing fields, it depends upon $\delta$. The resonance lines have characteristic features of ferromagnetic resonance. The intensity ($I (\Delta H_{pp})^2$) is used as an experimental parameter for investigating the effect of $\delta$. It allows to built a diagram closely connected to the phase diagram $T-\delta$. It suggests a ferromagnetic coupling depending upon $\delta$. When the (average) structure is tetragonal the low intensity is due to a magnetic polaron of low resistivity. In ranges where a phase separation is detected, the ferromagnetic coupling has a structural origin (DM or local anisotropy) with apparently a strong influence on the electrical resistivity.
PACS. 72.80.-r Conductivity of specific materials - 75.80.+q Magnetomechanical and magnetoelectric effects, magnetostriction - 76.50.+g Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance
(a) email: odier@cnrs-orleans.fr
Online publication: June 2, 1998
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