Current oscillation and low-field colossal magnetoresistance effect in phase-separated manganites.
Current oscillation and low-field colossal magnetoresistance effect in phase-separated manganites.
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DOI：
10.1103/physrevlett.94.157203
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发表时间：
2005-04
影响因子：
8.6
通讯作者：
M. Tokunaga;H. Song;Y. Tokunaga;T. Tamegai
中科院分区：
文献类型：
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作者：
M. Tokunaga;H. Song;Y. Tokunaga;T. Tamegai
在(La(1-y)Pr(Y))0.7Ca0.3MnO_3(y=0.7)和Nd(0.5)Ca(0.5)Mn(1-z)Cr(Z)O_3(z=0.03)晶体的相分离状态下，观察到了电流诱导从金属态到绝缘态的转变。在这种电流感应绝缘态上施加磁场会导致显著的低场负磁电阻效应[在H=1Koe时，Rho(H)/Rho(0)=10(-3)]。施加恒定电压也会导致欧姆关系在阈值电压以上击穿。在高于该阈值的电压下，可以观察到电流的振荡。这种振荡被一个简单的渗流传导路径局部切换模型很好地再现了。
Current-induced switching from a metallic to an insulating state is observed in phase-separated states of (La(1-y)Pr(y))0.7Ca0.3MnO3 (y=0.7) and Nd(0.5)Ca(0.5)Mn(1-z)Cr(z)O3 (z=0.03) crystals. The application of magnetic fields to this current-induced insulating state causes a pronounced low-field negative magnetoresistance effect [rho(H)/rho(0)=10(-3) at H=1 kOe]. The application of a constant voltage also causes the breakdown of the Ohmic relation above a threshold voltage. At voltages higher than this threshold value, oscillations in currents are observed. This oscillation is well reproduced by a simple model of local switching of a percolative conduction path.