Magnetoresistance effect element and Heusler alloy

A magnetoresistance effect element comprising:

• a first ferromagnetic layer;
• a second ferromagnetic layer;
• and
• a non-magnetic layer positioned between the first ferromagnetic layer and the second ferromagnetic layer, wherein
• at least one of the first ferromagnetic layer and the second ferromagnetic layer is a Heusler alloy in which a portion of elements of an alloy represented by the following general expression (1),
• (Co1-aX1a)2(Fe1-bY1b)αZβ (1)
• and in expression (1), X1 is a substitution element, in which
• Z is one or more elements selected from the group consisting of Mn, Cr, Al, Si, Ga, Ge, and Sn,
• α and β satisfy 2.3≤α+β, α<β, and 0.5<α<1.9,
• the substitution element is an element different from the Z element and has a smaller magnetic moment than Co,
• Y1 is one or more second substitution elements selected from the group consisting of elements having a smaller magnetic moment than Fe, and
• a and b satisfy 0<a<0.5 and b≥0.