Narrow track thin film head including magnetic poles machined by focused ion beam etching

A magnetic head comprising:

• a first shield layer formed on a substrate,
• a magnetoresistive sensor formed through an insulation layer on said first shield layer,
• a second shield layer formed through an insulation layer on said magnetoresistive sensor, which serves as a first write pole,
• a gap layer formed on said first write pole, and
• a second write pole formed on said gap layer,
• wherein a width of one of said first write pole and said second write pole is defined by machining of a focused ion beam, and
• a difference between said width of the edge of the first write pole and said width of the edge of the second write pole is less than or equal to 0.1 μm.

A magnetic head comprising:

• a first shield layer formed on a substrate,
• a magnetoresistive sensor formed through an insulation layer on said first shield layer,
• a second shield layer formed through an insulation layer on said magnetoresistive sensor,
• a first write pole,
• a gap layer formed on said first write pole, and
• a second write pole formed on said gap layer,
• wherein a width of one of said first write pole said second write pole is defined by machining of a focused ion beam, and
• a difference between said width of the edge of the first write pole and said width of the edge of the second write pole is less than or equal to 0.1 μm.

A magnetic head comprising:

• a first shield layer formed on a substrate,
• a magnetoresistive sensor formed through an insulation layer on said first shield layer,
• a second shield layer formed through an insulation layer on said magnetoresistive sensor, which serves as a first write pole, and
• a second write pole formed through an insulation layer on said first write pole,
• wherein said first write pole is machined by a focused ion beam so as to define one of a width of said first write pole and a width of said second write pole, and
• the difference between the width of the edge of the first write pole and the width of the edge of the second write pole at an air bearing surface is not more than 0.1 μm.

A magnetic head comprising:

• a first shield layer formed on a substrate,
• a magnetoresistive sensor formed through an insulation layer on said first shield layer,
• a second shield layer formed through an insulation layer on said magnetoresistive sensor,
• a first write pole, and
• a second write pole formed through an insulation layer on said first write pole,
• wherein one of said first write pole and said second write pole is machined by a focused ion beam so as to define a width of said one of said first write pole and said second write pole, and
• the difference between the width of the edge of the first write pole and the width of the edge of the second write pole at an air bearing surface is not more than 0.1 μm.