Faster vortex core switching with lower current density using three-nanocontact spin-polarized currents in a confined structure

We perform micromagnetic simulations on the switching of magnetic vortex core by using spin-polarized currents through a three-nanocontact geometry. Our simulation results show that the current combination with an appropriate current flow direction destroys the symmetry of the total effective energy of the system so that the vortex core can be easier to excite,resulting in less critical current density and a faster switching process. Besides its fundamental significance, our findings provide an additional route to incorporating magnetic vortex phenomena into data storage devices.     

Exchange interaction between vortex and antivortex

The dynamic properties of interacting vortex–antivortex pairs in thin film are studied by analytical calculations. Analytical expressions for the magnetization vector distribution of vortex–antivortex pairs and the trivortex states are given.The magnetic states of the vortices are treated as having rigid structures, i.e., the vortex maintains its spin distribution when moving. The trajectories of the vortex cores are calculated by the Thiele’s equation. It is found that the vortex–antivortex pair rotates around each other when they have opposite polarities, however, vortex and antivortex cores move along straight lines when they have the same polarity. The frequency of the rotation decreases with increasing the distance between the two cores of vortex–antivortex pair, and it has a lower value when a third vortex is introduced.     

Influence of Dzyaloshinskii-Moriya interaction on the magnetic vortex reversal in an off-centered nanocontact geometry

The influence of Dzyaloshinskii-Moriya interaction (DMI) on the vortex reversal driven by an out-of-plane spin-polarized current in an off-centered nanocontact structure is investigated. The simulation results show that DMI plays a vital role in vortex core reversal, including reversal current density, reversal velocity and reversal time. Under the influence of DMI, magnetic vortices still reverse polarity through the nucleation and annihilation of vortex and anti-vortex, with some peculiar characteristics. These results open up new possibilities for the application of magnetic vortex-based spin-transfer encryption nano-storage.     

具有尺寸限制的点接触结构自旋极化电流驱动下磁涡旋的稳态振荡

选取具有尺寸限制的点接触结构作为研究对象,采用Thiele方程对模型中磁涡旋在自旋极化电流作用下的动力学行为进行计算.计算表明磁涡旋可以在一定的电流密度范围内稳定旋转,该稳定旋转可以存在的电流密度范围与点接触区的大小和纳米点的尺寸有关.当磁涡旋核作稳态旋转时,其所处的轨道半径以及旋转频率都随电流密度的增加而增加,旋转频率可调节的范围随点接触尺寸的增加快速减小.