Patent ID: 8378437

Claim:
A magnetoresistive effect element comprising: a reference layer having an invariable magnetization which is perpendicular to a top surface of the reference layer; a recording layer having a variable magnetization which is perpendicular to the top surface of the reference layer; the top surface of the recording layer is parallel to the top surface of the reference layer; and a nonmagnetic layer formed between the reference layer and the recording layer, wherein the recording layer is made of a magnetic alloy containing at least one element of Fe, Co, and Ni and at least one element of Pt and Pd, and the magnetoresistive effect element has an element diameter D that satisfies the following expressions i and ii: D < 24 ⁢ ⁢ μ 0 M s 2 ⁢ N a ⁢ AK u i N a = ( 2 ⁢ ⁢ D / 3 ⁢ ⁢ t ) 2 ( 2 ⁢ ⁢ D / 3 ⁢ ⁢ t ) 2 - 1 ⁡ [ 1 - 1 ( 2 ⁢ ⁢ D / 3 ⁢ ⁢ t ) 2 - 1 ⁢ arc ⁢ ⁢ sin ( ( 2 ⁢ ⁢ D / 3 ⁢ ⁢ t ) 2 - 1 ( 2 ⁢ ⁢ D / 3 ⁢ ⁢ t ) ) ] ii where Ms is a saturation magnetization of a magnetic material of the recording layer, Ku is a magnetic anisotropy constant of the magnetic material of the recording layer, A is an exchange stiffness coefficient, t is a film thickness of the recording layer, μ 0 is a vacuum magnetic permeability, and Na is a demagnetization coefficient wherein the element diameter D is less than 80 nm.