通过电阻率、磁化曲线和电子自旋共振谱(ESR)的测量,对超大磁阻材料La2/3Ca1/3MnO3的绝缘体-金属(I-M)转变过程进行了研究.在磁场作用下,高温顺磁相的电阻率与绝热小极化子跃迁模式[ρ～BTexp(Ea/kT)]相吻合,低温铁磁相的电阻率与单磁振子散射模式(ρ～ρ0+AT2)相吻合,这意味着在I-M转变期间,小极化子和巡游载流子是共存的.基于磁有序过程引发小极化子退局域这一认识,用两相模型定量描述I-M转变期间的输运行为,在不同磁场下电阻率的计算结果与实验数据非常接近,有力证明了I-M转变是由于小极化子退局域和两种特殊的输运行为共存.
参考文献
| [1] | Helmolt R V;Wecker J;Holzapfel B et al.Giant negative magnetoresistance in perovskitelike La2/3Ba1/3MnOx ferromagnetic films[J].Physical Review Letters,1993,71:2331. |
| [2] | Jin S;Tiefel T H;McCormack M et al.Thousandfold change in resistivity in magnetoresistive La-Ca-Mn-O films[J].Science,1994,264:413. |
| [3] | ZhaoGM;ConderK;KellerH et al.Giant oxygen isotope shiftin the magnetoresistance perovskite Laq-x Cax MnO3+y[J].Nature,1996,381:676. |
| [4] | Zener C .Interaction between the d-shells in the transition metals. Ⅱ. Ferromagnetic compounds of manganese with perovskite structure[J].Physical Review,1951,82:403. |
| [5] | Anderson P W;Hasegawa H .Consideration on double exchange[J].Physical Review,1995,100:675. |
| [6] | Millis J;Littlewood P B;Shraiman B I .Double exchange alone does not explain the resistivity of La1 -xSrxMnO3[J].Physical Review Letters,1995,74:5144. |
| [7] | Sun Y.;Zhang YH.;Xu XJ. .Variable-range hopping of small polarons in mixed-valence manganites[J].Journal of Physics. Condensed Matter,2000(50):10475-10480. |
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