Numerical Study for Successive Ballistic Motion of Magnetization in Single Domain Particle Caused by Alternating Magnetic Fields

摘要

Recently, a ballistic switching of magnetization induced by applying a hard-axis field attracts much interests in the application of magnetic random access memories (MRAMs), because a switching time can be reduced to several-tens picoseconds order[1]. The maximum rotating angle of magnetization, θ{sub}(max), is obtained after an initial half period of the precession and gradually decreases due to a damping term. For a successful ballistic switching using a pulsed hard-axis field, the field strength should be large enough to rotate the magnetization crossing the hard in-plane axis. Reduction of the switching field strength is also important for the application of MRAM. In this study, we have numerically confirmed that the θ{sub}(max) can be enhanced by applying sinusoidal hard-axis field with a frequency much faster than a typical relaxation time (<1ns). In this case, the magnetic field exerted on the magnetization is temporally varying before a damping effect is appeared, so that the successive ballistic motion of magnetizaiton is expected.