Browse Prior Art Database

Magnetoresistive Head Element

IP.com Disclosure Number: IPCOM000087033D
Original Publication Date: 1976-Dec-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Cheatham, SD: AUTHOR [+2]

Abstract

This magnetoresistive (MR) head element combines shunt bias, AC bias and a longitudinally applied magnetic field to reduce output nonlinearity, thermal noise and barkhausen noise.

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Magnetoresistive Head Element

This magnetoresistive (MR) head element combines shunt bias, AC bias and a longitudinally applied magnetic field to reduce output nonlinearity, thermal noise and barkhausen noise.

In Fig. 1, the element is constructed on a ferrite substrate by depositing successive layers of aluminum oxide, titanium, nickel-iron and gold. The nickel- iron layer is used for its MR characteristic. The shunting titanium layer provides an appropriate bias to the nickel-iron layer when current is applied through the gold layer. The aluminum oxide insulates the three layers from the substrate and from a permanent magnet film deposited on a ferrite closure. When the closure and substrate are mated, the magnetic field (M), supplied by the permanent magnet film, longitudinally biases the nickel-iron film.

In Fig. 2, AC current is supplied to the element's titanium and nickel-iron films simultaneously. This gives the benefits of both shunt and AC biasing. In the E configuration shown, shunt bias provides an essentially linear output, while AC biasing assures that the output will be free of thermal noise. The longitudinal magnetic field supplied by the permanent magnet film greatly reduces barkhausen noise.

The head element and two resistors R form a bridge which provides zero voltage difference to the amplifier when balanced. An external magnetic field changes the element resistances, unbalances the bridge and applies a portion of the AC bias source voltage di...