Structural and Magnetic Properties of La 0.7 Sr 0.3 Mn 1-x Ni x O 3 (x=0.05, 0.1, 0.2, 0.3, 0.4)
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Structural and Magnetic Properties of La0.7Sr0.3Mn1-xNixO3 (x=0.05, 0.1, 0.2, 0.3, 0.4) Thomas F. Creel,1 Jinbo B. Yang,2 Mehmet Kahveci,3 Jagat Lamsal,3 Satish K. Malik,4 S. Quezado,4 B. W. Benapfl,5 H. Blackstead,5 O. A. Pringle,1 William B. Yelon,6 William J. James6 1
Department of Physics, Missouri University of Science and Technology, Rolla, MO, U.S.A. State Key Laboratory for Artificial Microstructure and Mesoscopic Physics and School of Physics, Peking University, Beijing 3 Department of Physics, University of Missouri, Columbia, MO, U.S.A 4 Departamento de Física Teórica e Experimental, UFRN, 59072-970 NATAL- RN, Brazil 5 Department of Physics, University of Notre Dame, IN, U.S.A. 6 Center for Materials Science Research, Missouri University of Science and Technology, Rolla, MO, U.S.A. 2
ABSTRACT We have studied the structural and magnetic properties of La0.7Sr0.3Mn1-xNixO3 (x=0.05, 0.10, 0.20, 0.30, and 0.40) perovskites using x-ray and neutron diffraction and magnetic measurements. To our knowledge, there exists no neutron diffraction data available for this group of perovskite compositions. Neutron (λ = 1.479Å) and x-ray (λ = 1.5481Å; Cu Kα) powder diffraction indicate that for x ≥ 0.1 all samples are two-phase with a rhombohedral perovskite structure (space group R-3c) and a small amount of NiO (space group Fm3m). Neutron diffraction data for the perovskite phase at 12K and 300K show ferromagnetic ordering for x ≤ 0.2 and antiferromagnetic ordering for x = 0.4. However, for x = 0.3, neutron diffraction data at 12K show coexisting ferromagnetic and antiferromagnetic ordering while at 300K no magnetic ordering is found. Magnetic measurements indicate that the Curie temperature decreases with increasing Ni content. The NiO phase for all samples was found to have antiferromagnetic ordering at 12K and 300K. The magnetic measurements are consistent with the neutron diffraction data and together indicate long-range magnetic ordering for samples at low temperature and transitions from ferromagnetic to paramagnetic to antiferromagnetic ordering for samples at room temperature.
INTRODUCTION There continues to be significant interest in the magnetic and electronic transport properties of manganese-based perovskite materials. In the earliest studies, complex ferromagnetic (FM) and antiferromagnetic (AFM) phases were found to exist, and more recently, colossal magnetoresistance and interesting magnetotransport properties have been discovered [1]-[3]. These mixed-valence perovskites have a myriad of applications that include cathodes for solid oxide fuel cells, catalysis and giant magneto-resistance materials [4]-[6]. The magnetic and transport properties of these manganites have been described using the double exchange mechanism of Mn3+-O-Mn4+, distorted perovskite structures caused by different ion sizes and electron-phonon coupling due to the Jahn-Teller effect of the Mn3+ ion [7]-[10]. The Mn3+ and
Mn4+ ions with itinerant and localized electrons in orbitals t2g e1g, and t2g e0g respectively, are described by
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