中国物理B ›› 2007, Vol. 16 ›› Issue (1): 258-265.doi: 10.1088/1009-1963/16/1/044
屈哲, 皮雳, 樊济宇, 谭舜, 张贝, 张锰, 张裕恒
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)
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".
中图分类号: (Magnetization curves, hysteresis, Barkhausen and related effects)