Zr-substituted perovskites La0.7Sr0.3 Mn1-x Zrx O3 with 0 ≤ x ≤ 0.20 were investigated by neutron diffraction (ND), magnetization, electric resistivity, and magnetoresistance measurements. ND refinements reveal that substituted Zr4+ goes only to the Mn site. Because of its large size, this leads to a Zr-solubility limit at x ≤ 0.10. The x ≤ 0.10 samples exhibit a rhombohedral structure (R3c) from 10 K to room temperature. For the x ≤ 0.10 samples, the cell parameters a and c, and volume increase continuously with increasing Zr content. In addition, the structural distortion of the Mn O6 octahedra increases with increasing Zr content. Zr-substituted La0.7 Sr0.3 Mn1-x Zrx O3 exhibits metallic behavior at low temperature. The field dependent resistivity suggests that electron-electron scattering is dominant and a two-magnon scattering process emerges with increasing temperature. The contribution from the two-magnon scattering in resistivity becomes larger with increasing Zr content. A maximum magnetoresistance (MRmax) of 35% is obtained for the x=0.03 sample at H=5 T. The MRmax shifts to a higher temperature region upon application of an external magnetic field.



Second Department


Keywords and Phrases

Electric conductivity; Low temperature effects; Magnetic field effects; Magnetization; Magnetoresistance; Neutron diffraction; Solubility; Substitution reactions; Transport properties; Zirconium; Cell parameters; External magnetic fields; Magnon scattering; Refinements; Perovskite

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Document Type

Article - Journal

Document Version

Final Version

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© 2007 American Institute of Physics (AIP), All rights reserved.

Publication Date

01 May 2007