Magnetic and high-pressure magnetotransport properties of cesium-substituted lanthanum calcium manganites |
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Authors: | G. Srinivasan T.P. Mullin D. Hanna A. Manivannan M.S. Seehra |
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Affiliation: | (1) Physics Department, Oakland University, Rochester, Michigan 48309, USA, US;(2) Physics Department, West Virginia University, Morgantown, West Virginia 26505, USA, US |
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Abstract: | ![]() The nature of the double-exchange (DE) interaction in lanthanum manganites is studied through chemical substitutions, Cs for La, and high-pressure measurements. Static and high-frequency magnetic measurements and high-pressure electrical transport studies were carried out on bulk polycrystalline and radio-frequency sputtered thin films of La0.7-xCsxCa0.3MnO3 for x=0-0.1. The samples are found to be cubic. Curie temperature Tc measurements provide evidence for bond-length-related weakening of DE as x is increased from 0 to 0.03. For higher x, the bond-angle-related changes lead to an increase in the strength of DE. High-pressure mangetoresistance data indicate both bond length and bond-angle-related increase of 10–20 K/GPa in Tc with pressure, with the largest increase measured for x=0.03. The rate of increase in the Curie temperature with pressure decreases with increasing Tc. Anomalies are observed in the magnetic parameters for x=0.03. The Cs-concentration dependence of the low-temperature saturation magnetization shows a minimum close to x=0.03. Ferromagnetic resonance studies at x-band reveal a 5% decrease in the g-value for x=0.03 relative to the end members (x=0 and 0.1). The low-field magnetostriction for x=0.03 indicates a relatively strong electron–phonon spin coupling compared to neighboring compositions. Received: 15 May 2000 / Accepted: 24 July 2000 / Published online: 9 November 2000 |
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Keywords: | PACS: 75.30.Cr 75.30.Et 75.70.-i 75.80.+q 76.50.+g |
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