Journal of Alloys and Compounds 479 (2009) 445–450 Contents lists available at ScienceDirect Journal of Alloys and Compounds journal homepage: www.elsevier.com/locate/jallcom Magnetic structure in the segregated phases Nd 0.93 MnO 2.96 N. Ihzaz a,b , M. Boudard c,d,∗ , H. Vincent d , M. Oumezzine a a Laboratoire de Physico-Chimie des Matériaux, Département de Physique, Faculté des Sciences de Monastir, 5019 Monastir, Tunisia b Institut Supérieur des Sciences Appliquées et de Technologie de Gabès, Rue Amor Ben El Khatab, 6029 Gabès, Tunisia c SIMAP/ENSEEG, UMR5614 CNRS/INPG/UJF, BP75, 38402 St. Martin d’Hères Cedex, France d LMGP, MINATEC Bâtiment INPG, UMR 5628 CNRS/INPG, 3 Parvis Louis Néel, BP 257, 38016 Grenoble Cedex 1, France article info Article history: Received 29 May 2008 Received in revised form 19 December 2008 Accepted 23 December 2008 Available online 4 January 2009 Keywords: Perovskites Crystal structure Symmetry Neutron diffraction Magnetic properties abstract We report complete information on a structural model (involving two perovskite phases with a slight dif- ferent chemical composition and magnetic ordering temperatures) that is introduced in order to interpret powder neutron diffraction (PND) and magnetic measurement on Nd 0.93 MnO 2.96 manganites. The mag- netic structure derived from PND data shows that the Mn magnetic sub-lattice for both phases become ordered below T N = 80 K corresponding to a canted ferromagnet with a spin arrangement (Cx, Fy,0). The Nd magnetic sub-lattice for both phases becomes polarized below T = 19 K having a unique ferromagnetic component parallel to the ferromagnetic component Fy of the Mn sub-lattice. Magnetic measurement can be interpreted considering that whereas the ferromagnetic components of Mn magnetic sub-lattice of both phases are antiferromagnetically coupled in the temperature range 19 –80 K, they appear to be ferromagnetically coupled below 19 K. This change is accompanied by an abrupt reverse of the magnetization as a function of the temperature near 19K. © 2009 Elsevier B.V. All rights reserved. 1. Introduction The physics of doped rare-earth manganites R 1-x A x MnO 3 , where R is the trivalent rare-earth ion and A is either a divalent alkaline-earth, a monovalent alkali metal or represents a deficiency in R (vacancy doping), has attracted much attention because of their distinctive properties, especially the colossal magnetoresistance (CMR) effect [1–5]. In particular two segregated phases with respec- tively antiferromagnetic (AFM) and ferromagnetic (FM) orders have been considered [6] in order to explain the CMR [7–9]. CMR prop- erties arise from a complicated micro (nano)-structure (involving inhomogeneities at different length scales ranging from micro- to manometer). In relation with this point, we remark that “Phase seg- regation” in manganites is meant sometimes as electronic phase segregation (e.g. metallic vs. insulator or ferromagnetic vs. anti- ferromagnetic phases) while in others it is meant for structural phase segregation (e.g. Pnma vs. R ¯ 3c phases). A detailed review of experimental evidence of phase segregation can be found in Dagotto et al. [10]. Such microstructure reflects directly in a com- plicated behaviour of the magnetic measurement. Manganite with Nd rare-earth ion also appears to exhibit an interesting and compli- cated magnetic behaviour (with change of sign of the magnetization as a function of temperature) which can be interpreted by con- ∗ Corresponding author. Tel.: +33 476 866617. E-mail address: mboudard@minatec.inpg.fr (M. Boudard). sidering different microstructures [11–14]. First paper interpreting negative magnetization in NdMnO 3+ı as a phase segregation effect was published by Bartolomé et al. [11] showing stray similarities with pioneer work of Chukalkin et al. who showed that negative magnetization is also related to phase segregation affect in garnet samples [15]. In Ref. [12], we interpreted the particular magnetic behaviour in Nd 0.93 MnO 2.96 samples by considering two canted AFM phases with nuclear and magnetic structures closely related to the one of the NdMnO 3 [16]. Main characteristic of NdMnO 3 magnetic structure is a weak FM component superimposed to an A-type AFM component. The complicated magnetic behaviour in Nd 0.93 MnO 2.96 was successfully explained by considering an AFM coupling between the FM components of two coexisting NdMnO 3 type phases. Magnetic and nuclear structure results were only briefly published in the Journal of Magnetic Materials and Magnetism [12] as a support of the interpretation of our magnetic measure- ments. The aim of this article is to present complete structural information. 1.1. Preliminar considerations Some important points have to be considered in relation to our work: - Ferrimagnetic coupling with compensation temperature in some spinel oxides was observed few decades ago [17]. Recently, a ferrimagnetic-like state with compensation temperature T comp 0925-8388/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2008.12.103