中国物理B ›› 2007, Vol. 16 ›› Issue (1): 258-265.doi: 10.1088/1009-1963/16/1/044

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Electric and magnetic behaviour in double doped La2/3+4x/3Sr1/3-4x/3Mn1-xMgxO3

屈哲, 皮雳, 樊济宇, 谭舜, 张贝, 张锰, 张裕恒   

  1. Structure Research Laboratory, University of Science and Technology of China, Hefei 230026, China
  • 收稿日期:2006-03-28 修回日期:2006-06-13 出版日期:2007-02-01 发布日期:2007-02-01
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos 10504029 and 10334090), and the State Key Project of Fundamental Research, China (Grant No 001CB610604).

Electric and magnetic behaviour in double doped La$_{2/3+4x/3}$Sr$_{1/3-4x/3}$Mn$_{1-x}$Mg$_{x}$O$_{3}$

Qu Zhe(屈哲), Pi Li(皮雳)†, Fan Ji-Yu(樊济宇), Tan Shun(谭舜), Zhang Bei (张贝), Zhang Meng(张锰), and Zhang Yu-Heng (张裕恒)   

  1. Structure Research Laboratory, University of Science and Technology of China, Hefei 230026, China
  • Received:2006-03-28 Revised:2006-06-13 Online:2007-02-01 Published:2007-02-01
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos 10504029 and 10334090), and the State Key Project of Fundamental Research, China (Grant No 001CB610604).

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摘要： The double-doped La2/3+4x/3Sr1/3-4x/3Mn1-xMgxO3 samples with fixed Mn3+/Mn4+ ratio equal to 2/1 are investigated by means of magnetism and transport measurements. Phase separation is observed at temperature higher than Tconset for x=0.10 and 0.15. For x=0.10, rather strong phase separation induces drastic magnetic random potential and results in the localization of carriers. Thus, the variable-range hopping process dominates. For other samples, there is no or only weak phase separation above Tconset. Thus, thermal activation mechanism is responsible for the high temperature transport behaviour. For x=0.20 and 0.25, unexpected AFM behaviour is observed at low temperature. All these results are well understood by considering the special role of the ``double-doping".

关键词: perovskite manganites, double doping, phase separation, variable-range hopping mechanism

Abstract: The double-doped La$_{2/3+4x/3}$Sr$_{1/3-4x/3}$Mn$_{1-x}$Mg$_{x}$O$_{3}$ samples with fixed Mn3+/Mn4+ ratio equal to 2/1 are investigated by means of magnetism and transport measurements. Phase separation is observed at temperature higher than Tconset for x=0.10 and 0.15. For x=0.10, rather strong phase separation induces drastic magnetic random potential and results in the localization of carriers. Thus, the variable-range hopping process dominates. For other samples, there is no or only weak phase separation above Tconset. Thus, thermal activation mechanism is responsible for the high temperature transport behaviour. For x=0.20 and 0.25, unexpected AFM behaviour is observed at low temperature. All these results are well understood by considering the special role of the ``double-doping".

Key words: perovskite manganites, double doping, phase separation, variable-range hopping mechanism

中图分类号:  (Magnetization curves, hysteresis, Barkhausen and related effects)

  • 75.60.Ej
61.66.Fn (Inorganic compounds) 64.75.-g (Phase equilibria) 72.20.Ee (Mobility edges; hopping transport) 72.80.Sk (Insulators) 76.30.-v (Electron paramagnetic resonance and relaxation)