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采用传统固相反应法制备钙钛矿型锰氧化物 (La0.8Eu0.2)4/3Sr5/3Mn2O7多晶样品, X-射线衍射分析表明, 样品(La0.8Eu0.2)4/3Sr5/3Mn2O7结构呈现良好的单相. 通过磁化强度随温度的变化曲线(M-T)、不同温度下磁化强度随磁场的变化曲线(M-H)和电子自旋共振谱发现: 在300 K以下, 随着温度的降低, 样品先后经历了二维短程铁磁有序转变 (TC2D ≈ 282 K)、三维长程铁磁有序转变(TC3D ≈ 259 K)、奈尔转变(TN ≈ 208K)和电荷有序转变(TCO ≈ 35 K); 样品 (La0.8Eu0.2)4/3Sr5/3Mn2O7在TN以下, 主要处于反铁磁态; 在TC3D达到370 K时, 样品处于铁磁-顺磁共存态, 在370 K以上时样品进入顺磁态. 此外, 分析电阻率随温度的变化曲线(ρ-T)得到: 样品在金属-绝缘转变温度(TP ≈ 80 K)附近出现最大磁电阻值, 其位置远离TC3D, 表现出非本征磁电阻现象, 其磁电阻值约为61%. 在TCO以下, 电阻率出现明显增长, 这是由于温度下降使原本在高温部分巡游的eg电子开始自发局域化增强所致. 通过对 (La0.8Eu0.2)4/3Sr5/3Mn2O7的ρ-T 曲线拟合, 发现样品在高温部分的导电方式基本遵循小极化子的导电方式.Samples of (La0.8Eu0.2)4/3Sr5/3Mn2O7 were prepared by solid state reaction method. X-ray diffraction patterns indicated that the sample shows no any asymmetry and no any trace of secondary phase. The magnetization curve as a function of temperature (M-T), the magnetization versus magnetic field (M-H) at different temperatures, and the electron spin resonance spectrum have been detected. The magnetization measurement reveals that with lowing temperature, all of the samples undergo a complex magnetic transition. They transform from the two-dimensional short-range ferromagnetic order at TC2D ≈ 282 K, and enter the three-dimensional long-range ferromagnetic state at TC3D ≈ 259 K. Then they step into the antiferromagnetic state at TN ≈ 208 K and enter electric charge temperature order at TCO ≈ 35 K. The antimagnetic phase is found in the sample (La0.8Eu0.2)4/3Sr5/3Mn2O7below TN. When TC3D=370 K, the paramagnetic phase and antimagnetic phase co-exist. When TC3D is above 370 K, only paramagnetic phase exists in the sample. Besides, through electrical resistivity versus temperature curve ρ-T, the sample shows the maximum magnetization electrical resistivity when metal-insulator transition temperature is reached TP ≈ 80 K, TP being far from TC3D. And the transition shows the phenomenon of intrinsic magnetization electrical resistance, MR ≈ 61%. The resistance begins to increase below TCO. Because of the lowing temperature, the itinerant electron eg becomes increasingly spontaneously localized. One can see from the fitted ρ-T curves that (La0.8Eu0.2)4/3Sr5/3Mn2O7 in high temperature range is in accordance with the small polaron mode range hopping conduction.
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Keywords:
- magnetic property /
- electrical property /
- metal-insulator transition /
- electron spin resonance
[1] Zhao J J, Xing R, Lu Y, Haosi B Y, Zhao M Y, Jin X, Zheng L, Ning W, Sun Y, Cheng Z H 2008 Chin. Phys. 17 2721
[2] Imada M, Fujimori A, Tokura Y 1998 Rev. Mod. Phys. 70 1039
[3] Zhao J J, Lu Y, Haosi B Y, Xing R, Yang R F, Li Q A, Sun Y, Cheng Z H 2008 Chin. Phys. 17 2717
[4] Jonker G H 1956 Physica 22 707
[5] Jonker G H, van Santen J H 1950 Physica 16 337
[6] Searle C W, Wang S T 1969 Can. J. Phys. 47 2703
[7] Ram R A M, Ganguly P, Rao C N R 1987 J. Sol. Stat. Chem. 70 82
[8] Kimura T, Tomioka Y, Kuwahara H, Asamitsu A, Tamura M, Tokura Y 1996 Science 274 1698
[9] Argyriou D N, Mitchell J F, Radaelli P G, Jorgensen J, Goodenough J, Cox D, Bordallo H 1999 Phys. Rev. B 59 8695
[10] Deisenhofer J, Braak D, Krug von Nidda H A, Hemberger J, Eremina R M, Ivanshin V A, Balbashov A M, Jug G, Loidl A, Kimura T, Tokura Y 2005 Phys. Rev. Lett. 95 257202
[11] Yang R F, Sun Y, He W, Li Q A, Cheng Z H 2007 Appl. Phys. Lett. 90 032502
[12] Battle P D, Green M A, Laskey N S, Millburn J E, Murphy L, Rosseinsky M J, Sullivan S P, Vente J F 1997 Mater. Chem. 7 977
[13] Zhang J, Wang F W, Zhang P L, Yan Q W 2000 Mater. Sci. Eng. B 76 6
[14] Joonghoe D, Kim W S, Hur N H 2001 Phys. Rev. B 65 024404
[15] Ma X, Kou Z Q, Di N L, Li Q A, Cheng Z H 2005 J. Magn. Magn. Mater. 285 439
[16] Wang F, Gukasov A, Moussa F, Hennion M, Apostu M, Suryanarayanan R, Revcolevschi A 2003 Phys. Rev. Lett. 91 47204
[17] Chen C X 2005 J. Inorg. Mater. 20 1 (in Chinese) [陈春霞 2005 无机材料学报 20 1]
[18] Wang H J, Zheng L, Xing R, Zhao J J, Lu Y, Cheng Z H 2012 Sin. China: Phys. Mech. Astron. 42 695 (in Chinese) [王洪金, 郑琳, 邢如, 赵建军, 鲁毅, 成昭华 2012 中国科学: 物理学 力学 天文学42 695]
[19] Zhao J J, Xing R, Lu Y, Hao S B Y E, Zhao M Y, Jin X, Zheng L, Ning W, Sun Y, Cheng Z H 2008 Chin. Phys. B 17 2721
[20] Zhou M, Wu H Y, Wang H J, Zheng L, Zhao J J, Lu Y 2012 Physica B 407 2219
[21] Liu L 2005 Ph. D. Dissertation (Wuhan: Huazhong University of Science and Technology) (in Chinese) [刘莉 2005 博士学位论文(武汉: 华中科技大学)]
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[1] Zhao J J, Xing R, Lu Y, Haosi B Y, Zhao M Y, Jin X, Zheng L, Ning W, Sun Y, Cheng Z H 2008 Chin. Phys. 17 2721
[2] Imada M, Fujimori A, Tokura Y 1998 Rev. Mod. Phys. 70 1039
[3] Zhao J J, Lu Y, Haosi B Y, Xing R, Yang R F, Li Q A, Sun Y, Cheng Z H 2008 Chin. Phys. 17 2717
[4] Jonker G H 1956 Physica 22 707
[5] Jonker G H, van Santen J H 1950 Physica 16 337
[6] Searle C W, Wang S T 1969 Can. J. Phys. 47 2703
[7] Ram R A M, Ganguly P, Rao C N R 1987 J. Sol. Stat. Chem. 70 82
[8] Kimura T, Tomioka Y, Kuwahara H, Asamitsu A, Tamura M, Tokura Y 1996 Science 274 1698
[9] Argyriou D N, Mitchell J F, Radaelli P G, Jorgensen J, Goodenough J, Cox D, Bordallo H 1999 Phys. Rev. B 59 8695
[10] Deisenhofer J, Braak D, Krug von Nidda H A, Hemberger J, Eremina R M, Ivanshin V A, Balbashov A M, Jug G, Loidl A, Kimura T, Tokura Y 2005 Phys. Rev. Lett. 95 257202
[11] Yang R F, Sun Y, He W, Li Q A, Cheng Z H 2007 Appl. Phys. Lett. 90 032502
[12] Battle P D, Green M A, Laskey N S, Millburn J E, Murphy L, Rosseinsky M J, Sullivan S P, Vente J F 1997 Mater. Chem. 7 977
[13] Zhang J, Wang F W, Zhang P L, Yan Q W 2000 Mater. Sci. Eng. B 76 6
[14] Joonghoe D, Kim W S, Hur N H 2001 Phys. Rev. B 65 024404
[15] Ma X, Kou Z Q, Di N L, Li Q A, Cheng Z H 2005 J. Magn. Magn. Mater. 285 439
[16] Wang F, Gukasov A, Moussa F, Hennion M, Apostu M, Suryanarayanan R, Revcolevschi A 2003 Phys. Rev. Lett. 91 47204
[17] Chen C X 2005 J. Inorg. Mater. 20 1 (in Chinese) [陈春霞 2005 无机材料学报 20 1]
[18] Wang H J, Zheng L, Xing R, Zhao J J, Lu Y, Cheng Z H 2012 Sin. China: Phys. Mech. Astron. 42 695 (in Chinese) [王洪金, 郑琳, 邢如, 赵建军, 鲁毅, 成昭华 2012 中国科学: 物理学 力学 天文学42 695]
[19] Zhao J J, Xing R, Lu Y, Hao S B Y E, Zhao M Y, Jin X, Zheng L, Ning W, Sun Y, Cheng Z H 2008 Chin. Phys. B 17 2721
[20] Zhou M, Wu H Y, Wang H J, Zheng L, Zhao J J, Lu Y 2012 Physica B 407 2219
[21] Liu L 2005 Ph. D. Dissertation (Wuhan: Huazhong University of Science and Technology) (in Chinese) [刘莉 2005 博士学位论文(武汉: 华中科技大学)]
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