A magnetoresistive sensor and a manufacturing method thereof are provided. The method includes: forming an initial reference layer in an annular shape, wherein the initial reference layer includes an anti-ferromagnetic layer and a ferromagnetic layer; performing a heat treatment on the initial reference layer, wherein the ferromagnetic layer is magnetized to have a magnetization direction oriented along a vortex path during a heating step of the heat treatment, and an exchange bias oriented along the vortex path is induced at an interface of the anti-ferromagnetic layer and the ferromagnetic layer during a cooling step of the heat treatment; patterning the initial reference layer to form separated reference layers, wherein the reference layers are respectively formed in a annular sector shape, and the reference layers are arranged along the vortex path; forming spacer layers and free layers to form magnetoresistive devices; routing the magnetoresistive devices to form the magnetoresistive sensor. |