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Six Acoustic Transducers for Acoustically Scanned Magnetoresistive Sensors

IP.com Disclosure Number: IPCOM000083313D
Original Publication Date: 1975-Apr-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 3 page(s) / 38K

Publishing Venue

IBM

Related People

Bajorek, CH: AUTHOR [+5]

Abstract

Acoustic transducers which allow optimum implementation of the interaction compatible with magnetoresistive sensor geometries, are provided as an optimization of the type discussed in an article entitled "Acoustically Scanned Magnetoresistive Transducer by D.A. Thompson. IBM Technical Disclosure Bulletin, Vol. 17, No. 10, March 1975, pages 3173 and 3174.

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Six Acoustic Transducers for Acoustically Scanned Magnetoresistive Sensors

Acoustic transducers which allow optimum implementation of the interaction compatible with magnetoresistive sensor geometries, are provided as an optimization of the type discussed in an article entitled "Acoustically Scanned Magnetoresistive Transducer by D.A. Thompson. IBM Technical Disclosure Bulletin, Vol. 17, No. 10, March 1975, pages 3173 and 3174.

Six specific transducer schemes are described, four of which use interdigital or single-phase thin-film transducers, the fifth being a bulkwave transducer, while the sixth is a combined bulk and surface-wave transwave transducer, while the sixth is a combined bulk and surface-wave transducer. Transducers:.

1.) Thin-film surface-wave transducers consisting of interdigital or single- phase arrays deposited directly on top of a single-crystal piezoelectric substrate (for example, quartz). In order to avoid static magnetoelastic interactions, which can give rise to undesirably large strain induced amisotropy fields in the magnetoresistive sensor, the single-crystal substrate should have isotropic thermal coefficients of thermal expansion in the plane of the substrate. (For example, an A-C cut single-crystal quartz substrate). The absence of planar anisotropies in the substrate will also minimize orientation constraints of the transducers relative to the magnetoresistive sensor, and simplify the excitation of well defined acoustic pulses.

2.) Thin-film surface-wave transducers consisting of interdigital or single- phase arrays deposited on top of a thin piezoelectric film (for example, zinc oxide) on top of an amorphous substrate (for example, thermally oxidized silicon, glass or amorphous quartz). The use of amorphous substrates will eliminate the problems due to planar substrate anisotropies described in part 1.), and will consequently simplify the fabrication of magnetoresistive films with optimum magnetic properties. The use of the transducer piezoelectric film combination will allow the excitation of acoustic pulses, which will couple to the surface of the substrates.

3.) Acoustically guided wave in a piezoelectric film or a thin nonpiezoelectric plate. This mode can easily...