Fundamental aspects of all-optical single pulse switching in nanometer-sized magnetic storage media

纳米级磁存储介质中全光单脉冲开关的基本原理

• 批准号: 439225584
• 负责人: Dr. Jakob Walowski
• 金额: --
• 依托单位: Institut für Physik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/439225584?language=en
• 关键词: Fundamental; aspects; optical; single; pulse

Increasing amounts of data for digital storage, call for new technological concepts enabling higher densities with faster writing speeds to the storage media. After over 40 years of miniaturization, conventional techniques for magnetic data storage are facing their limits. Essentially, storing information on a magnetic hard disk is setting the magnetization of smallest domains and thus creating bits. Conventionally, this is done by small electromagnets flying directly above the disk’s surface inducing a magnetic field. As the optimization possibilities using this method are technologically reaching an end, new approaches become interesting. All-optical helicity-dependent magnetization switching (AO-HDS) has the potential for further bit shrinking and at the same time to speed up the writing process. Our precedent studies with granular FePt hard disk media point to stochastic switching triggered by the Inverse Faraday Effect (IFE) as the major source of the deterministic switching mechanism with circularly polarized laser pulses, which we will overcome. I propose a research project performing AO-HDS switching experiment using circularly polarized femtosecond laser pulses in the wavelength range from near-infrared to midinfrared. In this study, the efficiency of the IFE with respect to different photon energies in granular media together with the interplay between the IFE and the magnetic circular dichroism will be elucidated. Using my expertise in time-resolved magneto-optical Kerr-effect (TR-MOKE) measurements will allow implementing these experiments alongside to further analyze the magnetization and switching dynamics on femto- to picosecond time scales. For the examination of plasmonic and dielectric near field amplification and switching enhancement, the required nanostructures at the interface to the disk media will be developed. Two collaborations with experimental groups will extend the analysis of the switching experiments by employing Kerr-Microscopy to image the magnetic structures after switching and to study the microscopic mechanism and origin of AO-HDS using Magnetic Force Microscopy. This project is embedded into existing successful theory collaborations in which the current tools developed for thermal spin modelling, ab-initio IFE calculations and thermal macrospin modelling will be extended to enhance their descriptive spectrum.

数字存储的数据量不断增加，需要新的技术概念来实现更高的密度和更快的写入速度到存储介质。经过40多年的小型化，传统的磁数据存储技术正面临着极限。从本质上讲，在磁性硬盘上存储信息是设置最小域的磁化强度，从而产生比特。传统上，这是通过在磁盘表面直接飞行的小型电磁铁产生磁场来完成的。随着使用这种方法的优化可能性在技术上达到极限，新的方法变得有趣起来。全光螺旋相关磁化开关（AO-HDS）具有进一步缩小比特的潜力，同时可以加快写入过程。我们先前对颗粒状FePt硬盘介质的研究表明，由逆法拉第效应（IFE）触发的随机开关是圆极化激光脉冲确定性开关机制的主要来源，我们将克服这一问题。我提出了一个研究项目，利用近红外到中红外波长范围内的圆偏振飞秒激光脉冲进行AO-HDS开关实验。在本研究中，将阐明颗粒介质中不同光子能量下的光子激元效率，以及光子激元与磁圆二色性之间的相互作用。利用我在时间分辨磁光克尔效应（TR-MOKE）测量方面的专业知识，将允许实施这些实验，同时进一步分析飞至皮秒时间尺度上的磁化和开关动力学。为了检测等离子体和介电体近场放大和开关增强，需要在磁盘介质界面处开发所需的纳米结构。两个与实验组的合作将扩展开关实验的分析，使用kerr显微镜对开关后的磁性结构进行成像，并使用磁力显微镜研究AO-HDS的微观机制和起源。该项目嵌入到现有成功的理论合作中，其中目前开发的热自旋建模、ab-initio IFE计算和热宏观自旋建模工具将得到扩展，以增强其描述谱。