On the absence of bipolarons in manganese perovskites

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• 作者：Chipara ; M. ; Skomski ; R. ; Liou ; S.-H. ; Dowben ; P.A. ; Adenwalla ; S.
• 关键词：76.50+g ; 75.30.Gw ; Electron spin resonance ; Polaron/bipolaron ; Electronic materials ; Manganese perovskites
• 刊名：Materials Letters
• 出版年：2005
• 期刊代码：59_0167577x
• 类别：ms
• 出版时间：February, 2005
• 卷：59
• 期：2-3
• 页码：297-301
• 文件大小：256 K

摘要

The paramagnetic phase of La_0.65Ca_0.35MnO₃ and La_0.65Pb_0.35MnO₃ powders was investigated by electron spin resonance. The resonance spectra, for a range of temperatures, was used to examine the presence of polarons and bipolarons. The resonance lines are compatible with the presence of polarons (g芒芒芒2), but the characteristic high-spin bipolaron lines (g芒芒芒4) are absent. The results are inconsistent with the presence of high-spin bipolarons. The evidence with respect to low-spin bipolarons is less conclusive, although the temperature dependence of the resonance line parameters speaks against the presence of low-spin bipolarons.