Strain-induced insulator state and giant gauge factor of La0.7Sr0.3CoO3 films.
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.
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IFW Dresden, Institute for Metallic Materials, Helmholtzstrasse 20, 01069 Dresden, Germany.
Herklotz
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A
Nenkov
K
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Schultz
L
L
Dörr
K
K