All-optical switching in granular ferromagnets caused by magnetic circular dichroism.
All-optical switching in granular ferromagnets caused by magnetic circular dichroism.
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DOI：
10.1038/srep30522
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发表时间：
2016-07-28
影响因子：
4.6
通讯作者：
Chantrell RW
中科院分区：
文献类型：
--
作者：
Ellis MO;Fullerton EE;Chantrell RW
使用圆偏振飞秒激光脉冲的磁记录是一种新兴技术，其允许比现有场驱动方法快得多的写入速度。然而，驱动铁磁体中磁化转换的机制尚不清楚。最近的理论表明，光与磁化介质的相互作用在介质内感应出光磁场，称为逆法拉第效应。在这里，我们表明，一种替代机制，驱动的热激发的各向异性能垒和不同的能量吸收取决于偏振，可以创建一个净磁化强度超过一系列的激光脉冲在一个合奏的单畴晶粒。只有一个小的差异，需要达到实验观察到的磁化强度水平的吸收和模型不排除逆法拉第效应的作用，但消除了必要性，即光磁场的强度是10特斯拉。
Magnetic recording using circularly polarised femto-second laser pulses is an emerging technology that would allow write speeds much faster than existing field driven methods. However, the mechanism that drives the magnetisation switching in ferromagnets is unclear. Recent theories suggest that the interaction of the light with the magnetised media induces an opto-magnetic field within the media, known as the inverse Faraday effect. Here we show that an alternative mechanism, driven by thermal excitation over the anisotropy energy barrier and a difference in the energy absorption depending on polarisation, can create a net magnetisation over a series of laser pulses in an ensemble of single domain grains. Only a small difference in the absorption is required to reach magnetisation levels observed experimentally and the model does not preclude the role of the inverse Faraday effect but removes the necessity that the opto-magnetic field is 10 s of Tesla in strength.