Method of manufacturing a magnetoresistive element

A method of manufacturing a magnetoresistive element, the magnetoresistive element comprising:

• a nonmagnetic layer having a first surface and a second surface that face toward opposite directions;
• a pinned layer disposed adjacent to the first surface of the nonmagnetic layer, a direction of magnetization in the pinned layer being fixed;
• and a free layer disposed adjacent to the second surface of the nonmagnetic layer, a direction of magnetization in the free layer changing in response to an external magnetic field, wherein a current for detecting magnetic signals is fed in a direction intersecting a plane of each of the forgoing layers, at least one of the pinned layer and the free layer includes a Heusler alloy layer made of a Heusler alloy and having two surfaces that are quadrilateral in shape and face toward opposite directions, and the Heusler alloy layer includes one crystal grain that touches four sides of one of the two surfaces of the Heusler alloy layer, the method comprising the steps of:
• forming a layered film that will be the magnetoresistive element after undergoing patterning and heat treatment, the layered film including a film to be the pinned layer, a film to be the nonmagnetic layer, and a film to be the free layer, wherein at least one of the film to be the pinned layer and the film to be the free layer includes a film to be the Heusler alloy layer;
• patterning the layered film so that the film to be the Heusler alloy layer has two surfaces that are quadrilateral in shape and face toward opposite directions;
• and
• performing the heat treatment on the layered film after the step of patterning, so that crystal grains included in the film to be the Heusler alloy layer grow and one crystal grain that touches four sides of one of the two surfaces of the film to be the Heusler alloy layer is thereby formed.