Electron Spin Resonance and Neutron Diffraction Studies of Nd0.5-xPrxSr0.5MnO3 (x = 0.125, 0.25)

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• 作者：C. Autret-Lambert ; Z. Jirak ; M. Gervais ; N. Poirot ; F. Gervais ; N. Raimboux ; P. Simon ; F. Bour&eacute ; e ; G. Andr&eacute
• 刊名：Chemistry of Materials
• 出版年：2007
• 出版时间：October 30, 2007
• 年：2007
• 卷：19
• 期：22
• 页码：5222 - 5229
• 全文大小：296K
• 年卷期：v.19,no.22(October 30, 2007)
• ISSN：1520-5002

文摘

Effects of Pr substitution on the magnetic properties of perovskite manganite Nd_0.5Sr_0.5MnO₃ havebeen investigated by measurements of electron spin resonance, magnetization, and powder neutrondiffraction. These experiments evidence a complex phase-segregated state at low temperatures andcoexistence of different ferromagnetic (FM) and antiferromagnetic (AFM) arrangements. Four temperatureregions are distinguished, similar for both studied samples Nd_0.5-xPr_xSr_0.5MnO₃ (x = 0.125, 0.25). Aroundthe room temperature and above there is a region of a single orthorhombic perovskite Ibmm phase ofparamagnetic (PM) state, where the first signatures for FM clusters can be indicated in the electron spinresonance spectra below ~1.1 T_C (T_C = 260 K). Between T_C and T_C2 (230 K for x = 0.25), a newtetragonal perovskite I4/mcm phase of FM long range order is formed at the expense of the PMorthorhombic phase. Below T_C2, the FM order is established in both crystallographic phases, and theamount of the tetragonal phase for x = 0.25 achieves a maximum close to 45% of the sample. Finally,below ~160 K, strongly distorted perovskite domains with the CE and A-type kinds of AFM order (T_N= 150 K for x = 0.25) are segregated while the orthorhombic FM phase quickly vanishes. At the lowesttemperatures, the two structurally distorted AFM domains make up 72% of the x = 0.25 sample, and theremaining 28% belongs to the tetragonal FM domains.