Computational Studies of Dynamical Phenomena in Nanoscale Ferromagnets

9871455 Novotny这是一项理论和计算研究基金，旨在利用高性能计算机和最先进的算法探索纳米级磁铁的特性。过去十年的进步为理解和设计纳米尺度的材料提供了可能性。与此同时，在计算算法和计算机体系结构方面有了巨大的进步，这使得现实地研究这些材料成为可能。磁性纳米颗粒和超薄膜的具体研究对可靠的超高密度磁存储具有重要意义。在这种情况下，单个比特的信息将被存储在单畴纳米级磁颗粒中。因此，了解这些畴的稳定性，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。该基金将为纳米级铁磁体的磁滞和热驱动磁化逆转模型开发新的算法。本研究的目的将是提高我们对实际铁磁材料在非零温度下受限几何结构中的动力学现象的理解。要建模的材料包括超薄膜、晶须和纳米尺寸的单畴颗粒。将使用的模型包括具有有限自旋各向异性的时钟和连续自旋模型、静磁相互作用的效应、具有缺陷和淬火无序的系统、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。其中包括投影动力学和蒙特卡罗吸收马尔可夫链算法。本文还提出了利用朗格万微磁方法进行有限温度模拟的连续自旋模型的大规模研究和进一步发展。这项研究的成功完成将有助于更好地理解真实纳米级磁性材料的磁化开关动力学。所开发的算法应具有广泛的应用前景。这是一项理论和计算研究基金，旨在利用高性能计算机和最先进的算法探索纳米尺度上磁铁的特性。过去十年的进步为理解和设计纳米尺度的材料提供了可能性。与此同时，在计算算法和计算机体系结构方面有了巨大的进步，这使得现实地研究这些材料成为可能。磁性纳米颗粒和超薄膜的具体研究对可靠的超高密度磁存储具有重要意义。在这种情况下，单个比特的信息将被存储在单畴纳米级磁颗粒中。因此，了解这些畴的稳定性，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. ***