飞秒激光超快热诱导全光磁化反转研究进展
|
摘要
现代信息技术的飞速发展对数据存储容量及存储速度的要求越来越高。然而,随着存储技术朝超高密度、超高速度方向发展,一方面,磁记录密度发展也已接近超顺磁极限(百Gbpsi量级),要进一步提高记录密度必须采用高矫顽力的记录介质,但目前的磁头无法提供能克服高矫顽力的写入磁场;另一方面,磁记录速度因受限于磁化反转速度而进展缓慢。因此,发展新型的超高密度、超高速度记录技术,已成为现代信息技术领域的新挑战。飞秒激光超快加热全光磁化反转的实现,为开发超高密度、超高速信息存储器件提供了方向,成为当前磁信息存储的研究热点。此项新型磁记录技术无需外加磁场,直接利用飞秒线偏振光超快加热磁光材料GdFeCo亚铁磁薄膜实现全光磁化反转。此磁化反转基于亚铁磁晶格间的自旋交换作用,发生在皮秒超快时间尺度内。该技术无需外磁场作用,存储器结构简单、成本较低,并且存储速度极快,有望实现超高速磁记录,因此被认为是发展新一代超高速存储技术的重要成果。然而,要加快研发出新型飞秒激光超快加热全光磁记录技术,不仅需要理解飞秒激光超快热诱导磁化反转的起源物理机制,进而搞清其磁化反转的具体实现过程,而且需要搞清该全光磁化反转的实现条件以及影响因素,具体包括对所用材料的结构参数和材料特性的要求,对所用激光的脉冲宽度和激发功率的要求,以及这些材料参数和激光条件的变化对超快热诱导全光磁化反转的反转速度的影响。只有理解了超快热诱导磁化反转的机理,弄清全光磁化反转的实现条件以及影响因素,才能真正促进新型超高密度、超高速全光磁记录技术的发展。本文首先介绍了稀土-过渡金属GdFeCo亚铁磁合金在飞秒激光作用下发生超快热诱导全光磁化反转的技术特点,讨论了实现超快热诱导磁化反转的物理机制,并进一步分析总结了超快热诱导磁化反转对材料特性以及激发激光的要求。最后指出传统超快热诱导磁化反转材料——GdFeCo无定形合金薄膜在超高密度存储上存在的局限因素,并对发展超高记录密度、超高记录技术进行了展望。
The rapid development of modern information technology demands more and more data storage capacity and storage speed. However,with the development of storage technology toward ultra-high density and super-high speed,on the one hand,the magnetic recording density has also approached the superparamagnetic limit( 100 Gbpsi). To further improve the recording density,a recording medium with high coercivity must be adopted,but the current magnetic head can not provide a writing magnetic field which can overcome the high coercivity. On the other hand,the magnetic recording speed has slowed down due to the magnetization reversal speed. Therefore,the development of new ultra-high density,ultra-high speed recording technology has become a new challenge in the field of modern information technology.The realization of femtosecond laser ultrafast thermally induced all-optical magnetization switching paved the way to develop the ultra-high density ultrafast-rate recording material,and thus became a hot topic of magnetic information storage research. The new magnetic recording technique uses femtosecond linearly polarized light to heat magneto-optical material GdF eCo ferromagnetic thin films directly to achieve all-optical magnetization switching,which is based on spin exchange between ferromagnetic lattices and occurs in picosecond ultrafast time scale. It is considered to be an important achievement in the development of a new generation of ultra-high-speed storage technology because of its simple structure,low cost,and high storage speed.However,in order to promote the realization of the new all-optical magnetic recording technology,it is necessary not only to understand the physical mechanism of the origin of the ultrafast thermally induced magnetization switching of femtosecond laser,but also to clarify the specific realization process of the magnetization switching,and to clarify the realization conditions and influencing factors of the all-optical magne-tization switching. Requirements for structural parameters and material properties of the materials used,as and the pulse width and flunence,as well as the effects of these material parameters and laser conditions on the switching speed of ultrafast thermally induced all-optical magnetization switching. Only by understanding the mechanism of ultrafast thermally induced magnetization switching and the influencing factors of all-optical magnetization switching can we really promote the development of new ultra-high density and ultra-high speed all-optical magnetic recording technology.Here the technical characteristics and physics mechanism of ultrafast thermal induced magnetization switching for rare earth-transition metal GdFeCo ferrimagnetic films are discussed in detail. The requirements of material properties and pump laser for ultrafast thermal induced magnetization switching are further studied. Finally,an obvious barrier to high density recording is pointed for the use of large amorphous structures,and the solution to the issue is further proposed. The results are expected to help to develop new ultrahigh-density and ultrafast-rate recording material and technology.
The rapid development of modern information technology demands more and more data storage capacity and storage speed. However,with the development of storage technology toward ultra-high density and super-high speed,on the one hand,the magnetic recording density has also approached the superparamagnetic limit( 100 Gbpsi). To further improve the recording density,a recording medium with high coercivity must be adopted,but the current magnetic head can not provide a writing magnetic field which can overcome the high coercivity. On the other hand,the magnetic recording speed has slowed down due to the magnetization reversal speed. Therefore,the development of new ultra-high density,ultra-high speed recording technology has become a new challenge in the field of modern information technology.The realization of femtosecond laser ultrafast thermally induced all-optical magnetization switching paved the way to develop the ultra-high density ultrafast-rate recording material,and thus became a hot topic of magnetic information storage research. The new magnetic recording technique uses femtosecond linearly polarized light to heat magneto-optical material GdF eCo ferromagnetic thin films directly to achieve all-optical magnetization switching,which is based on spin exchange between ferromagnetic lattices and occurs in picosecond ultrafast time scale. It is considered to be an important achievement in the development of a new generation of ultra-high-speed storage technology because of its simple structure,low cost,and high storage speed.However,in order to promote the realization of the new all-optical magnetic recording technology,it is necessary not only to understand the physical mechanism of the origin of the ultrafast thermally induced magnetization switching of femtosecond laser,but also to clarify the specific realization process of the magnetization switching,and to clarify the realization conditions and influencing factors of the all-optical magne-tization switching. Requirements for structural parameters and material properties of the materials used,as and the pulse width and flunence,as well as the effects of these material parameters and laser conditions on the switching speed of ultrafast thermally induced all-optical magnetization switching. Only by understanding the mechanism of ultrafast thermally induced magnetization switching and the influencing factors of all-optical magnetization switching can we really promote the development of new ultra-high density and ultra-high speed all-optical magnetic recording technology.Here the technical characteristics and physics mechanism of ultrafast thermal induced magnetization switching for rare earth-transition metal GdFeCo ferrimagnetic films are discussed in detail. The requirements of material properties and pump laser for ultrafast thermal induced magnetization switching are further studied. Finally,an obvious barrier to high density recording is pointed for the use of large amorphous structures,and the solution to the issue is further proposed. The results are expected to help to develop new ultrahigh-density and ultrafast-rate recording material and technology.
引文
1 Hamann H,Martin Y,Wickramashinghe H. Applied Physics Letter,2004,84,810.
2 Stanciu C,Tsukamoto A,Kimel A,et al. Physical Review Letter,2007,99,217204.
3 Kryder M,Gage E,Mc Daniel T,et al. Proceedings of the IEEE,2008,96,1810.
4 Pan L,Bogy D. Nature Photon,2009,3,189.
5 Kirilyuk A,Kimel A,Rasing T. Review of Modern Physics,2010,82,2731.
6 Schreck E,Li D,Canchi S,et al. IEEE Transactions on Magnetics,2014,50,3300406.
7 Richter H,Parker G,Staffaron M,et al. IEEE Transactions on Magnetics,2014,50,3001707.
8 Ostler T,Barker J,Evans R,et al. Nature Communications,2012,3,666.
9 Radu I,Vahaplar K,Stamm C,et al. Nature,2011,472,205.
10 Mentink J,Hellsvik J,Afanasiev D,et al. Physical Review Letter,2012,108,057202.
11 Barker J,Atxitia U,Ostler T,et al. Scientific Reports,2013,3,32621.
12 Graves C,Reid A,Wang T,et al. Nature Materials,2013,12,293.
13 Richard F,Ostler T,Chantrell R,et al. Applied Physics Letter,2014,104,0824101.
14 Mangin S,Gottwald M,Lambert C,et al. Nature Materials,2014,13,286.
15 Lambert C,Mangin S,Varaprasad B,et al. Science,2014,345,1337.
16 Liu T,Wang T,Reid A,et al. Nano Letters,2015,15,6862.
17 Atxitia U,Ostler T,Chantrell R,et al. Applied Physics Letter,2015,107,92402.
18 Xu C,Ostler T,Chantrell R. Physical Review B,2016,93,054302.
19 Gorchon J,Yang Y,Bokor J. Physical Review B,2016,94,020409.
20 Chen J,He L,Wang J,et al. Physical Review Applied,2017,7,021001.
21 Gorchon J,Lambert C,Yang Y,et al. Applied Physics Letters,2017,111,042401.
22 Moreno R,Ostler T,Chantrell R,et al. Physics Review B,2017,96,014409.
2 Stanciu C,Tsukamoto A,Kimel A,et al. Physical Review Letter,2007,99,217204.
3 Kryder M,Gage E,Mc Daniel T,et al. Proceedings of the IEEE,2008,96,1810.
4 Pan L,Bogy D. Nature Photon,2009,3,189.
5 Kirilyuk A,Kimel A,Rasing T. Review of Modern Physics,2010,82,2731.
6 Schreck E,Li D,Canchi S,et al. IEEE Transactions on Magnetics,2014,50,3300406.
7 Richter H,Parker G,Staffaron M,et al. IEEE Transactions on Magnetics,2014,50,3001707.
8 Ostler T,Barker J,Evans R,et al. Nature Communications,2012,3,666.
9 Radu I,Vahaplar K,Stamm C,et al. Nature,2011,472,205.
10 Mentink J,Hellsvik J,Afanasiev D,et al. Physical Review Letter,2012,108,057202.
11 Barker J,Atxitia U,Ostler T,et al. Scientific Reports,2013,3,32621.
12 Graves C,Reid A,Wang T,et al. Nature Materials,2013,12,293.
13 Richard F,Ostler T,Chantrell R,et al. Applied Physics Letter,2014,104,0824101.
14 Mangin S,Gottwald M,Lambert C,et al. Nature Materials,2014,13,286.
15 Lambert C,Mangin S,Varaprasad B,et al. Science,2014,345,1337.
16 Liu T,Wang T,Reid A,et al. Nano Letters,2015,15,6862.
17 Atxitia U,Ostler T,Chantrell R,et al. Applied Physics Letter,2015,107,92402.
18 Xu C,Ostler T,Chantrell R. Physical Review B,2016,93,054302.
19 Gorchon J,Yang Y,Bokor J. Physical Review B,2016,94,020409.
20 Chen J,He L,Wang J,et al. Physical Review Applied,2017,7,021001.
21 Gorchon J,Lambert C,Yang Y,et al. Applied Physics Letters,2017,111,042401.
22 Moreno R,Ostler T,Chantrell R,et al. Physics Review B,2017,96,014409.