Evolution of the Modes of a Magnetic Tunnel Junction upon a Change in the Direction of the External Magnetic Field

An experimental study is performed of the effect the value and direction of an external magnetic field has on the magnetization of a free layer in magnetic tunnel junctions 100, 150, and 250 nm in diameter. Two free layer modes are found in samples with a diameter of 100 nm. The first mode is less sensitive to the value and direction of the external magnetic field than the second, which is shifted in the frequency domain. Nonuniform magnetization of the free layer in weak fields is observed upon an increase in the geometric size of the magnetic tunnel junctions, and a mode insensitive to the direction of the external magnetic field is identified. A macrospin model is obtained of the behavior of the homogeneous mode of a free layer’s shape (disk or ellipse) at a constant value and different directions of the external magnetic field.