Magnetic storage device provided with magnetoresistive element

A magnetic storage device, comprising:

• a magnetoresistive element including a stacked structure of a recording layer, a tunnel barrier layer, and a reference layer, the recording layer including a first magnetic layer, the reference layer including a second magnetic layer;
• and
• a control unit, wherein
• an in-plane shape of the recording layer is a shape in which a rectangle circumscribing the in-plane shape and having a minimum area includes a short side and a long side which have mutually different lengths, and
• when writing to the recording layer is performed, the control unit applies a voltage pulse to the magnetoresistive element while applying an effective magnetic field in a direction of the short side in a plane of the recording layer,
• wherein the effective magnetic field expressed as Heff satisfies a relation of 0.2×Hkeff<|Heff|<Ms(Ny−Nx), and
• wherein Hkeff is an effective perpendicular magnetic field due to a perpendicular magnetic anisotropy, Ms is a saturation magnetization of the recording layer, Nx is a demagnetizing factor of a direction of the long side, and Ny is a demagnetizing factor of the direction of the short side.