Switching of magnetization by nonlinear resonance studied in single nanoparticles
Switching of magnetization by nonlinear resonance studied in single nanoparticles
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DOI：
10.1038/nmat946
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发表时间：
2003-08-01
期刊：
影响因子：
41.2
通讯作者：
Mailly, D
中科院分区：
文献类型：
--
作者：
Thirion, C;Wernsdorfer, W;Mailly, D
磁性粒子的磁化反转是磁性数据存储的基本问题之一。技术进步要求理解纳秒时间尺度上的动态磁化反转过程。需要新的战略来克服目前的限制。例如，通过增加磁各向异性，可以将磁化态(超顺磁性极限)的热稳定性问题推低到更小的颗粒尺寸。然后需要高场来反转磁化，这在目前的设备中是很难实现的。在这里，我们提出了一种新的方法来克服这一局限性。远低于开关场的恒定外加磁场与射频(RF)场脉冲相结合，可以逆转纳米颗粒的磁化。利用超导量子干涉器件(MicroSQUID)技术，在直径为20 nm的钴颗粒上验证了该方法的有效性。这种方法的其他应用可能是磁区壁成核或去钉扎。
Magnetization reversal in magnetic particles is one of the fundamental issues in magnetic data storage. Technological improvements require the understanding of dynamical magnetization reversal processes at nanosecond time scales. New strategies are needed to overcome current limitations. For example, the problem of thermal stability of the magnetization state (superparamagnetic limit) can be pushed down to smaller particle sizes by increasing the magnetic anisotropy. High fields are then needed to reverse the magnetization, which are difficult to achieve in current devices. Here we propose a new method to overcome this limitation. A constant applied field, well below the switching field, combined with a radio-frequency (RF) field pulse can reverse the magnetization of a nanoparticle. The efficiency of this method is demonstrated on a 20-nm-diameter cobalt particle by using the microSQUID (superconducting quantum interference device) technique. Other applications of this method might be nucleation or depinning of domain walls.