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Characterization of the torsional piezoelectriclike response of tantalum trisulfide associated with charge-density-wave depinning

We have studied the frequency and voltage dependences of voltage-induced torsional strains in orthorhombic TaS3 [V. Y. Pokrovskii, S. G. Zybtsev, and I. G. Gorlova, Phys. Rev. Lett. 98, 206404 (2007)] by measuring the modulation of the resonant frequency of an rf cavity containing the sample. The strain has an onset voltage below the charge-density-wave (CDW) threshold voltages associated with changes in shear compliance and resistance, suggesting that the strain is associated with polarization of the CDW rather than CDW current. Measurements with square-wave voltages show that the strain is very sluggish, not even reaching its dc value at a frequency of 0.1 Hz, but the dynamics appears to be very sample dependent. By applying oscillating torque while biasing the sample with a dc current, we have also looked for strain-induced voltage in the sample ; none is observed at the low biases where the voltage-induced strains first occur, but an induced voltage is observed at higher biases, probably associated with a strain-dependent CDW conductance.

charge density waves; piezoresistance; tantalum compounds; torsion

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