Effect of stress induced anisotropy on SAL-biased MR head performance
The effect of magnetostriction (MS) on the device characteristics of soft-adjacent-layer (SAL) biased magnetoresistive (MR) head was investigated. As MS changes from -7/spl times/10/sup -7/ to 1.77/spl times/10/sup -6/, the magnetic track width increases from 1.26 to 1.83 /spl mu/m. Asymmetry of bias point, output sensitivity, and output amplitude are also affected by the stress induced anisotropy. The variation of magnetostriction (/spl Delta//spl lambda/=2/spl times/10/sup -6/) induces the change in bias field by 60 Oe associated with the estimated stress of +800 MPa on the MR stripe.
Effect of magnetostriction on bias fields in self‐biased MR heads
The effect of magnetostriction on the bias conditions in self‐biased magnetoresistive (MR) heads is reported. In self‐biased MR heads where the bias field is derived from the sense current, the optimum bias point is where the head delivers the maximum output per unit input current. The optimum point depends on the element and head geometry, demagnetizing effects, and the permeability of the MR film. During head construction and operation the MR film is subjected to various sources of stress which can directly affect the permeability of the film and thus the position of this optimum bias point. Many self‐biased MR heads were fabricated using MR elements made from thin (<1000 A) oriented NiFe films with the magnetostriction coefficient close to but varied around zero. The results show quite a marked effect and a correlation between as‐deposited measurements and completed device performance. When the magnetostriction is negative the bias current has to be driven to higher values to achieve the defined optimu...
Magnetorestive measurement of magnetostriction in permalloy
The authors demonstrate a simple technique for determining magnetostriction in Permalloy films. It is capable of measuring values as low as +or-(1*10/sup -7/) in unpatterned films or patterned microstripes as thin as 10 nm. The method utilizes the inverse magnetostriction effect, using magnetoresistive detection to measure changes in film anisotropy induced by application of anisotropic strain. Samples are prepared in bar form, the center of which is deflected in a bending fixture in order to generate strain on the film. The determination of magnetostriction involves measurement of the width of the magnetoresistance versus applied field transfer characteristic of the film stripe as a function of bar center deflection using a simple benchtop apparatus. The technique is used routinely to measure magnetostriction both in as-deposited films and in fully processed magnetoresistor elements for use in magnetic recording applications. >