Effects of uniform magnetic fields on shielded MR sensors

• Published in: IEEE transactions on magnetics Vol. 27; no. 6; pp. 4701 - 4703
• Main Authors: Feng, J.S., Tippner, J., Kinney, B.G., Lee, J.H., Smith, R.L., Chue, C.
• Format: Journal Article
• Language: English
• Published: IEEE 01.11.1991
• Subjects: Distortion measurement; Hard disks; Helium; Magnetic field measurement; Magnetic heads; Magnetic sensors; Magnetic shielding; Magnetoresistance; Saturation magnetization; Shape
• ISSN: 0018-9464; 1941-0069
• DOI: 10.1109/20.278920

Standard thin-film techniques were used to construct the shielded magnetoresistive (MR) sensors with soft-adjacent-layer biasing. The authors show the three shield designs included in these tests: a tall and asymmetric shield pair with magnetic leads, a tall and asymmetric shield without the magnetic leads, and a short and symmetric structure. The authors discuss the effects of an externally applied magnetic field which can change the biasing of a magnetoresistive sensor. Under large-signal conditions, this produces preferential saturation of one polarity of the readback signal and changes the amount of waveform distortion. In a shielding MR sensor for hard disk applications, the sensitivity to external fields is affected by the shapes of the shields: tall shields are more sensitive to axial fields; asymmetrically shaped shields can increase the sensitivity to radial fields by converting them to axial fields at the sensor. Moderate fields can sometimes induce small, systematic changes into the small-signal spatial sensitivity.< >