Computational Studies of Dynamical Phenomena in Nanoscale Ferromagnets

9871455 Novotny这是一个理论和计算研究资助，旨在探索使用高性能计算机和最先进的算法在纳米尺度上的磁体的属性。 过去十年的进步为在纳米尺度上理解和设计材料开辟了可能性。 与此同时，在计算算法和计算机架构方面也取得了巨大的进步，这使得现实地研究这些材料成为可能。 对磁性纳米粒子和磁性薄膜的深入研究，对于实现可靠的超高密度磁存储具有重要意义。 在这种情况下，单个比特的信息将存储在单域纳米级磁性颗粒中。 因此，了解这些区域的稳定性，它们的动力学性质以及它们在有限温度下的行为是至关重要的。 这需要对技术上重要的磁性材料的现实模型进行密集的大规模数值模拟。 该基金将开发纳米级铁磁体的磁滞和热驱动磁化反转模型的新算法。 本研究的材料目标是提高我们对非零温度下限制几何结构中真实的铁磁材料动力学现象的理解。 模拟的材料包括薄膜、晶须和纳米级单畴颗粒。 所使用的模型包括有限自旋各向异性的时钟和连续自旋模型，静磁相互作用的影响，缺陷和淬火无序系统，亚铁磁体模型，和量子自旋模型。 为了研究这些模型，将进一步开发新的算法。 这些算法包括投影动力学和蒙特卡罗吸收马尔可夫链算法。 它还建议启动大规模的连续自旋模型的研究，并进一步发展，朗之万微磁学方法或有限温度模拟。 这项研究的成功完成将导致更好地了解在真实的纳米磁性材料的磁化开关的动力学。 开发的算法应该具有广泛的应用。 这是一项理论和计算研究资助，旨在使用高性能计算机和最先进的算法探索纳米尺度上的磁体特性。 过去十年的进步为在纳米尺度上理解和设计材料开辟了可能性。 与此同时，在计算算法和计算机架构方面也取得了巨大的进步，这使得现实地研究这些材料成为可能。 对磁性纳米粒子和磁性薄膜的深入研究，对于实现可靠的超高密度磁存储具有重要意义。 在这种情况下，单个比特的信息将存储在单域纳米级磁性颗粒中。 因此，了解这些区域的稳定性，它们的动力学性质以及它们在有限温度下的行为是至关重要的。 这需要对技术上重要的磁性材料的现实模型进行密集的大规模数值模拟。 ***

9871455 Novotny This is a theoretical and computational research grant which aims to explore the properties of magnets on the nanometer scale using high performance computers and state-of-the-art algorithms. Advances in the past decade have opened up the possibility of understanding and designing materials at the nanometer scale. At the same time there have been tremendous advances in computational algorithms and computer architectures which make it possible to realistically study these materials. The specific study of magnetic nanoparticles and ultrathin films is of importance for reliable ultrahigh-density magnetic storage. In this case a single bit of information will be stored in a single-domain nanoscale magnetic particle. Consequently, it is vitally important to understand the stability of these domains, their dynamical properties, and their behavior at finite temperatures. This requires intensive large-scale numerical simulations of realistic models of technologically important magnetic materials. This grant will develop novel algorithms for hysteresis and thermally driven magnetizatin reversal models of nanoscale ferromagnets. The materials objective of this research will be to improve our understanding of dynamical phenomena in real ferromagnetic materials in restricted geometries at nonzero temperatures. The materials to be modeled include ultrathin films, whiskers and nanometer-sized single-domain particles. The models to be used include the clock-and continuum-spin models with finite spin anisotropy, effects of magnetostatic interactions, systems with defects and quenched disorder, models of ferrimagnets, and quantum spin models. To study these models, novel algorithms will be further developed. These include the Projective Dynamics and the Monte Carlo with Absorbing Markov Chain algorithms. It is also proposed to initiate large-scale studies of continuum- spin models using, and further developing, Langevin micromagnetic methods f or finite-temperature simulations. Successful completion of this research will lead to a better understanding of the dynamics of magnetization switching in real nanoscale magnetic materials. The algorithms developed should have broad application. %%% This is a theoretical and computational research grant which aims to explore the properties of magnets on the nanometer scale using high performance computers and state-of-the-art algorithms. Advances in the past decade have opened up the possibility of understanding and designing materials at the nanometer scale. At the same time there have been tremendous advances in computational algorithms and computer architectures which make it possible to realistically study these materials. The specific study of magnetic nanoparticles and ultrathin films is of importance for reliable ultrahigh-density magnetic storage. In this case a single bit of information will be stored in a single-domain nanoscale magnetic particle. Consequently, it is vitally important to understand the stability of these domains, their dynamical properties, and their behavior at finite temperatures. This requires intensive large-scale numerical simulations of realistic models of technologically important magnetic materials. ***