| 摘要 |
<p>PROBLEM TO BE SOLVED: To enable a high reproduction output, a low noise level, a high S/N ratio and a low error rate, by forming an undercoat layer of a specific material of a predetermined thickness, thereby improving crystallinity and heat resistance of a magnetoresistive element, and improving a magnetoresistance change rate after the magnetoresistive element is formed and heat-treated. SOLUTION: Any one of 0.2-0.6 nm thick Ta, 0.2-1.5 nm thick Hf and 0.2-2.5 nm thick Zr is used for an undercoat layer 101. For instance, when Ta is used, an MR ratio is increased by 5% or more when the film thickness is 0.2-20 nm. The reason for this is that a part of an NiFe layer/Cu layer/NiFe layer is improved in crystallinity and accordingly improved in heat resistance, and a heat treatment after a magnetoresistive element is formed restricts disturbances in the vicinity of the Cu layer. An exchange coupling magnetic field is high when the film thickness is 0.2 nm or larger. A coercive force is so small as 50e or lower when the film thickness is 0.2-6 nm. The thickness of Ta satisfying all of the MR ratio, exchange coupling magnetic field and coercive force is accordingly 0.2-6 nm.</p> |
