ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

5pEA6. Techniques and instruments for investigating the ultrasonic analogs of magnetooptic effects.

Vladimir V. Gudkov

Inst. of Metal Phys. of Russian Academy of Sci., 18 Kovalevskaya St., GSP-170, Ekaterinburg 620219, Russia

Magnetoacoustic phenomena involving alteration of the polarization of a transverse wave (namely, the ultrasonic analogs of the Faraday and Cotton--Mouton effects) have been found in yttrium iron garnet [H. Matthews and R. C. LeCraw, Phys. Rev. Lett. 8, 397 (1962); B. Luthi, Phys. Lett. 3, 285 (1963)]. As the ellipticity E and the angle F of rotation of the polarization plane are rather large in magneto-ordered materials, it was possible to make the first measurements using distortion of the exponential decay of the ultrasonic echo pulses in the oscilloscope screen. After discovering these effects in metals, a precise technique for E and F evaluation has been required. A technique for measuring F has been suggested by Boyd and Gavenda [Phys. Rev. 152, 645 (1966)]. It is based on measurements of amplitude versus magnetic field for two cases: field parallel and antiparallel to the wave vector. In the present paper both some original generalizations of this technique as well as a device which enables simultaneous measurements of F and E are reported. In addition, an instrument for visual observation of the ellipsoid of polarization and the direction of the major ellipsoid axis is described.