Josephson current-assisted reversal of a single-domain nanoscale ferromagnet driven by cosine chirp pulse

Abstract

We study the microwave-induced magnetization reversal in two systems, the microwave-driven nanomagnet (NM-MW) and the nanomagnet coupled to a Josephson junction under the microwave field (NM-JJ-MW). The frequency of the applied cosine chirp pulse (CCP) changes nonlinearly with time to match the magnetization precession frequency. The coupling between the nanomagnet and Josephson junction reduces the magnetization switching time as well as the optimal amplitude of the microwave field as a result of manipulating the magnetization via Josephson-to-magnetic energy ratio G. The reversal effect in NM-JJ-MW is sufficiently robust against changes in pulse amplitude and duration. In this system, the increase of G decreases the possibility of the non-reversing magnetic response as the Gilbert damping increases without further increase in the external microwave field. We also discuss the magnetic response of the nanomagnet driven by the ac field of two Josephson junctions in which the time-dependent frequency is controlled by the voltage across the junctions. Our results provide a controllable scheme of magnetization reversal that might help to realize fast memory devices.

Thermal effect on microwave pulse-driven magnetization switching of Stoner particle

“…For the larger volume of nanoparticles, the parameters of cosine CMP remain constant for a wide range of temperatures which is useful practically. It is mentioned that there is a very recent study that demonstrates how to generate such cosine CMP in practice [71] and furthermore, several technologies [72,73] are available to generate such cosine CMP. It is suggested to simulate magnetization switching for a real nanoparticle and thus obtain the optimal parameters, later these parameters can be employed for all the same nano-particles of the device.…”