Acoustoelectric currents in manganite thin films (original) (raw)

Anomalous Acoustoelectric Effect in La0.67Ca0.33MnO3 Films

Physical Review Letters, 2001

We have studied acoustoelectric (AE) effect produced by surface acoustic waves (SAW) in a monolithic layered structure, composed of piezodielectric LiNbO 3 substrate and La 0.67 Ca 0.33 MnO 3 film. The experiments unexpectedly revealed in the longitudinal AE effect an anomalous contribution, invariant upon reversal of SAW propagation, which coexists with the ordinary (odd in wave vector) effect. The anomalous effect dominates near the metal-insulator transition, while the ordinary effect prevails at high and low temperatures. We show that the anomalous effect is caused by strong modulation of the film conductivity produced by the SAW elastic deformations. PACS numbers: 72.50.+b, 77.65.Dq, 75.30.Vn Typeset using REVT E X 1

Acoustic and acoustoelectric studies of manganite films

Journal of Magnetism and Magnetic Materials, 2002

We report on acoustic and acoustoelectric (AE) studies of La 0:67 Ca 0:33 MnO 3 (LCMO) films deposited on a LiNbO 3 substrate. Surface acoustic wave (SAW) attenuation in the LCMO films has been measured at different sound frequencies in the wide temperature range. Our measurements confirm the hole-like conductivity in La 0:67 Ca 0:33 MnO 3 films and reveal an anomalous (even in the SAW wave vector) contribution to the AE effect, which coexists with the ordinary (odd) effect. The anomalous AE effect is shown to be due to a strong modulation of the film conductivity produced by elastic deformations carried by the SAW. r 2002 Elsevier Science B.V. All rights reserved.

Acoustomagnetic pulse experiments in LiNbO3∕Mn12 hybrids

Applied Physics Letters, 2006

We report here on the influence of surface acoustic waves ͑SAWs͒ on the magnetization of a Mn 12-acetate single crystal. The crystal was mounted on the surface of a piezoelectric LiNbO 3 substrate containing an interdigital transducer for the excitation of SAWs. The magnetization of the crystal was measured using a rf superconducting quantum interference device with a time resolution of 1 s. The piezoelectric material was excited by SAW pulses of different frequencies produced by applying microwave pulses to the transducer. Our data show that molecular magnets onto the LiNbO 3 surface can be used as very sensitive detectors of the SAW frequency and intensity.

Novel nonreciprocal acoustic effects in antiferromagnets

Europhysics Letters (EPL), 1999

The possible occurrence of nonreciprocal acoustic effects in antiferromagnets in the absence of an external magnetic field is investigated using both (i) a microscopic formulation of the magnetoelastic interaction between spins and phonons and (ii) symmetry arguments. We predict for certain antiferromagnets the existence of two new nonreciprocal (non-time invariant) effects: A boundary-condition induced nonreciprocal effect and the occurrence of transversal phonon modes propagating in opposite directions having different velocities. Estimates are given and possible materials for these effects to be observed are suggested. PACS numbers: 72.55 +s, 73.50.Rb, 85.70.Ec Introduction It is well known in optics that the coupling of light to the order parameter in a ferromagnet mediates nonreciprocal effects such as the Faraday effect [1]. The Faraday effect in ferromagnets appears as a rotation of the plane of polarization of light which is incident along the axis of magnetization. An analogous effect in acoustics (the so-called acoustic Faraday effect) was first predicted by Kittel [2]. Subsequently, it was verified experimentally [3] that in a ferromagnet, circularly polarized phonons of different sense have

The Nonlinear Acoustoelectric Effect in a Superlattice

Communications in Physics, 2012

The acoustoelectric effect in a superlattice (SL) is investigated for an acoustic wave whose wavelength lambda=2pi/q\lambda =2\pi/ qlambda=2pi/q is smaller than the mean free path lll of the electrons and hypersound in the region qlgg1ql\gg1qlgg1. (where $ q$ is the acoustic wave number) . A nonlinear dependence of the acoustoelectric current jacj^{ac}jac on the constant electric field EEE is obtained by using the classical Boltzmann kenetic equation. The analytical expression for the acoustoelectric current jacj^{ac}jac is calculated for constant of momentum relaxation time. Numerical calculations is done, and the result is discussed for a typical GaAs/AlGaAs SL. It is noted that when the electric field is negative the current jacj^{ac}jac decreases, reaches a minimum and rises. On the other hand, when the electric field is positive the current increases, reaches a maximum and then falls off. A similar observation has been noted for an acoustoelectric interaction in a multilayered structure resulting from the analysis of $...

Nonlinear acoustoelectric and acoustooptic effects in semiconductor layered systems

2001 IEEE Ultrasonics Symposium. Proceedings. An International Symposium (Cat. No.01CH37263)

We study both theoretically and experimentally the interaction of intense surface acoustic waves with an electron and an electron-hole plasma of a quantum well. The experiments performed on hybrid semiconductor-piezocrystal structures exhibit strong nonlinear acoustoelectric and acoustooptic effects due to the formation of moving electron and electron-hole wires, respectively. We show theoretically that the nonlinear interaction of a SAW with a photogenerated electron-hole plasma qualitatively differs from the case of an unipolar electron system. For low temperatures, we consider the regime when the intense SAW forms moving quantum wires and quantum dots and predict a novel quantum acoustic phenomenon, selfinduced acoustic transparency.

The Anisotropy Induced by a Magnetostriction in Exchange-Biased Two-Layer Films

METALLOFIZIKA I NOVEISHIE TEKHNOLOGII, 2016

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