Tosado Jacob, Dhakal Tara, Biswas Amlan
Department of Physics, University of Florida, Gainesville, FL 32611, USA.
J Phys Condens Matter. 2009 May 13;21(19):192203. doi: 10.1088/0953-8984/21/19/192203. Epub 2009 Apr 22.
We have measured the strain dependent transport properties of phase separated manganite thin films. We subjected (La(1-y)Pr(y))(1-x)Ca(x)MnO(3) thin films grown on NdGaO(3)(110) substrates to direct external mechanical stress using a three-point beam bending method. The resultant change in resistance reveals a colossal piezoresistance (CPR) in manganites. Our experiments reveal that phase separation is a necessary but not sufficient condition for CPR. The maximum CPR is observed only when the phase boundaries are free to move in the fluid-like phase separated state. Our results show that both long-range strain interactions and quenched disorder play an important role in micrometer scale phase separation in manganites, albeit in different temperature ranges.
我们测量了相分离锰氧化物薄膜的应变相关输运性质。我们使用三点梁弯曲法，对生长在钕镓酸镧（110）衬底上的（镧（1 - y）镨（y））（1 - x）钙（x）锰氧化物薄膜施加直接的外部机械应力。电阻的最终变化揭示了锰氧化物中存在巨大的压阻效应（CPR）。我们的实验表明，相分离是产生CPR的必要但不充分条件。只有当相界在类流体相分离状态下能够自由移动时，才会观察到最大的CPR。我们的结果表明，长程应变相互作用和淬火无序在锰氧化物的微米尺度相分离中都起着重要作用，尽管作用的温度范围不同。
