I. Yatsyk, D. V. Mamedov, A. V. Shestakov, I. I. Fazlizhanov, R. M. Eremina, S. I. Andronenko, A. V. Pyataev, S. Vadnala, S. Asthana, S. K. Misra
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The Curie temperatures for the various samples were estimated from the characteristics of the variable-temperature EPR spectra. The EPR data indicated the presence of Griffiths phases in the samples with <i>x</i> = 0.2, 0.3, 0.4, 0.5, 0.6, from which the respective Griffiths temperatures were determined. The activation energies were estimated here from the EPR data using the hopping model. The EPR linewidth behavior is found to be consistent with that predicted by the bottlenecked spin-relaxation model. The perovskite La<sub>0.5</sub>Eu<sub>0.2</sub>Sr<sub>0.3</sub>MnO<sub>3</sub> is potentially useful in the design of magnetocaloric refrigeration units as a working fluid, since its Curie temperature <i>T</i><sub>C</sub> is found to be close to the room temperature. The various ferromagnetic components in the samples observed here have been resolved only by the technique of EPR, not possible by other techniques.</p></div>","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"55 9","pages":"1199 - 1219"},"PeriodicalIF":1.1000,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"EPR Studies of Rare-Earth Manganites La0.7−xEuxSr0.3MnO3 (x = 0.1–0.7)\",\"authors\":\"I. Yatsyk, D. V. Mamedov, A. V. Shestakov, I. I. Fazlizhanov, R. M. Eremina, S. I. Andronenko, A. V. Pyataev, S. Vadnala, S. Asthana, S. K. 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The activation energies were estimated here from the EPR data using the hopping model. The EPR linewidth behavior is found to be consistent with that predicted by the bottlenecked spin-relaxation model. The perovskite La<sub>0.5</sub>Eu<sub>0.2</sub>Sr<sub>0.3</sub>MnO<sub>3</sub> is potentially useful in the design of magnetocaloric refrigeration units as a working fluid, since its Curie temperature <i>T</i><sub>C</sub> is found to be close to the room temperature. 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引用次数: 0
摘要
利用 X 波段电子顺磁共振(EPR)技术研究了温度范围为 30 至 500 K 的铕稀土锰矿 La0.7-xEuxSr0.3MnO3(x = 0.0-0.7)。此外,在各种样品中还发现了两到三种铁磁相共存的现象。只有在 x = 0.1、0.2 和 0.3 的样品中才观察到第三种铁磁相。各种样品的居里温度是根据变温 EPR 光谱的特征估算出来的。EPR 数据表明 x = 0.2、0.3、0.4、0.5、0.6 的样品中存在格里菲斯相,并由此确定了各自的格里菲斯温度。这里的活化能是利用跳跃模型从 EPR 数据中估算出来的。发现 EPR 线宽行为与瓶颈自旋松弛模型预测的一致。由于发现过氧化物 La0.5Eu0.2Sr0.3MnO3 的居里温度 TC 接近室温,因此将其作为工作流体在磁致制冷装置的设计中具有潜在的用途。这里观察到的样品中的各种铁磁性成分只有通过 EPR 技术才能分辨出来,而其他技术则无法做到这一点。
EPR Studies of Rare-Earth Manganites La0.7−xEuxSr0.3MnO3 (x = 0.1–0.7)
The Europium rare-earth manganites, La0.7−xEuxSr0.3MnO3 (x = 0.0–0.7), were investigated by the technique of X-band electron paramagnetic resonance (EPR) in the temperature range from 30 to 500 K. As the temperature was lowered, the various samples made transitions from paramagnetic to ferromagnetic phases. Furthermore, coexistence of anywhere from two to three ferromagnetic phases in the various samples was found. The third ferromagnetic phase was observed only in the samples with x = 0.1, 0.2, 0.3. The Curie temperatures for the various samples were estimated from the characteristics of the variable-temperature EPR spectra. The EPR data indicated the presence of Griffiths phases in the samples with x = 0.2, 0.3, 0.4, 0.5, 0.6, from which the respective Griffiths temperatures were determined. The activation energies were estimated here from the EPR data using the hopping model. The EPR linewidth behavior is found to be consistent with that predicted by the bottlenecked spin-relaxation model. The perovskite La0.5Eu0.2Sr0.3MnO3 is potentially useful in the design of magnetocaloric refrigeration units as a working fluid, since its Curie temperature TC is found to be close to the room temperature. The various ferromagnetic components in the samples observed here have been resolved only by the technique of EPR, not possible by other techniques.
期刊介绍:
Applied Magnetic Resonance provides an international forum for the application of magnetic resonance in physics, chemistry, biology, medicine, geochemistry, ecology, engineering, and related fields.
The contents include articles with a strong emphasis on new applications, and on new experimental methods. Additional features include book reviews and Letters to the Editor.