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. ***
