抄録
The characteristics of the output vs. applied field (ΔV-H) of spin valve (SV) sensors with longitudinal biasing magnets are studied by using a micromagnetic model. In the case of sensors without biasing magnets, a hysteresis arises in the ΔV-H curves owing to an irreversible motion of the domain wall. When the product of the saturation flux density Bs and the thickness t of the biasing magnets are equal to or larger than the Bs·t values of the free layer, the ΔV-H curves are reversible. When the Bs·t values of the magnets rise, the sensitivity of the sensors falls. Compared with an anisotropic MR sensor (MR/Ta/SAL) with the same MR height and track width, an SV sensor is about six times as sensitive, assuming that the resistivity change Δρ for SV is three times as large. The reasons for the higher sensitivity are the larger Δρ, the lower demagnetizing field, and the lower shunting loss, which results from an SV sensor not having a Ta layer or SAL.
