Planar Hall resistance ring sensor based on NiFe/Cu/IrMn trilayer structure

We have investigated the sensitivity of a planar Hall resistance sensor as a function of the ring radius in the trilayer structure Ta(3)/IrMn(10)/Cu(0.2)/ NiFe(10)/Ta(3) (nm). The diagonal components of magnetoresistivity tensor in rectangular prism corresponding to anisotropic magnetoresistance are few ten times larger than that of off-diagonal component corresponding to planar Hall resistance. However, it is noteworthy that the resultant contribution is governed by the off-diagonal components due to the cancellation of diagonal components in the self-balanced bridge configuration. Both the experimental and theoretical results show that the sensitivity varies linearly with the ring radius. In multi-ring architecture, the circumference can be increased to a limit, which consequently enhances sensitivity. We found the sensitivity of the investigated 7-rings planar Hall to be more than 600 μV/Oe.