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Title: Influence of thermal processing on magnetotransport characteristics of NdSr{sub 2}Mn{sub 2}O{sub 7+δ}

Highlights: • The NdSr{sub 2}Mn{sub 2}O{sub 7+δ} compounds with different oxygen non-stoichiometry were prepared. • According to XRD analysis, all the oxides were completely single-phase. • The strong competition between different types of magnetic exchange interactions was revealed. • The samples demonstrate semiconducting behavior over the explored temperature range. • A large negative magnetoresistance effect for all the compounds below 200 K was observed. - Abstract: Background: Influence of oxygen non-stoichiometry on magnetic and electric properties of the compounds has not almost been studied yet. Aim: Synthesis of a number of the NdSr{sub 2}Mn{sub 2}O{sub 7+δ} samples subjected to various thermal processing in air atmosphere and investigation of their structure, oxygen non-stoichiometry, electrical and magnetic properties. Method: The compounds obtained have been characterized by using X-ray diffraction (XRD) analysis, a modified gravimetric method, vibrating sample magnetometry (VSM) and standard DC four-probe method. Results: It was established that additional firing of the samples at different temperatures leads to essential changes in the oxygen non-stoichiometry. The noticeable magnetoresistance (MR) effect is observed for all the compounds below 200 K and increases monotonically as the temperature decreases. The MR values for the compounds as a function of oxygen content vary nonlinearly. The largestmore » MR value of 380% at the 5 K and magnetic field of 7 T was achieved for the sample with the oxygen non-stoichiometry of δ = 0.03. Conclusions: The results observed are discussed in the assumption of ferromagnetic cluster formation in the compounds.« less
Authors:
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Publication Date:
OSTI Identifier:
22475823
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Research Bulletin; Journal Volume: 67; Other Information: Copyright (c) 2015 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; EXCHANGE INTERACTIONS; MAGNETIC FIELDS; MAGNETIC PROPERTIES; MAGNETORESISTANCE; MANGANATES; NEODYMIUM COMPOUNDS; OXIDES; STOICHIOMETRY; STRONTIUM COMPOUNDS; SYNTHESIS; VIBRATING SAMPLE MAGNETOMETERS; X-RAY DIFFRACTION