Rata A D, Herklotz A, Nenkov K, Schultz L, Dörr K
IFW Dresden, Institute for Metallic Materials, Helmholtzstrasse 20, 01069 Dresden, Germany.
Phys Rev Lett. 2008 Feb 22;100(7):076401. doi: 10.1103/PhysRevLett.100.076401. Epub 2008 Feb 20.
A strain-induced change of the electrical conductivity by several orders of magnitude has been observed for ferromagnetic La(0.7)Sr(0.3)CoO(3) films. Tensile strain is found to drive the narrow-band metal highly insulating. Reversible strain applied using a piezoelectric substrate reveals huge resistance modulations including a giant piezoresistive gauge factor of 7000 at 300 K. Magnetization data recorded for statically and reversibly strained films show moderate changes. This indicates a rather weak strain response of the low-temperature Co spin state. We suggest that a strain-induced static Jahn-Teller-type deformation of the CoO(6) units may provide a localization mechanism that also has impact on electronic transport in the paramagnetic regime.
已观察到铁磁体La(0.7)Sr(0.3)CoO(3)薄膜因应变导致电导率变化几个数量级。发现拉伸应变会使窄带金属变为高绝缘状态。使用压电衬底施加的可逆应变显示出巨大的电阻调制，包括在300 K时高达7000的巨压阻系数。对静态和可逆应变薄膜记录的磁化数据显示出适度变化。这表明低温Co自旋态的应变响应相当微弱。我们认为，CoO(6)单元的应变诱导静态 Jahn-Teller 型变形可能提供一种局域化机制，这也会影响顺磁态下的电子输运。
