| 摘要 |
In a method for measurement of very small local magnetic fields, in particular of local magnetic stray fields produced by magnetic beads, at least one magnetoresistive element is used. The element includes a hard-magnetic reference layer and a soft-magnetic sensor layer, whose magnetization can be rotated to a parallel position or an antiparallel position with respect to the reference layer magnetization, and whose output signal which can be tapped off is dependent on the position of the sensor layer magnetization with respect to the reference layer magnetization. In this case, the magnetization of the sensor layer is saturated by way of an external saturation magnetic field in a direction at right angles to the reference layer magnetization, after which the magnetic field is switched off or reduced to such an extent that the magnetization of the sensor layer passes through a critical point as it comes out of saturation, at which critical point the rotation direction of the sensor layer magnetization can be influenced via an existing local magnetic field that is to be measured. Magnetoresistive elements are provided in the associated device and, in particular, are connected to form a bridge. |
