Inter-American Materials Collaboration: Thermodynamic Properties of Thin Films of Magnets and Liquid Helium

这个美洲材料合作项目研究了磁性化合物和液氦薄膜的热力学性质。该项目汇集了由D。朗道，美国模拟物理中心。美国格鲁吉亚州和J.A. Plascak在巴西贝洛奥里藏特的米纳斯吉拉斯联邦大学。 针对磁性介观结构解决的主要问题是：i）高质量磁性纳米膜结构的横向尺寸如何控制其磁性; ii）原子台阶、岛等的影响，这种薄膜的磁性行为; iii）作为薄膜厚度的函数的热力学行为的演变。 对液氦的研究集中在使用经典的“磁性”模型，这些模型被认为与氦处于相同的普适性类别。计算机模拟是通过使用连续自旋系统的Monte Carlo方法，再加权程序和自旋动力学的内禀时间演化的相关性。 计算机模拟是越来越重要的，因为它们能够确定统计物理学中许多模型的属性，而这些模型并不适合精确解。这种合作促进了计算机模拟培训和初级项目参与者的国际接触。该奖项得到了材料研究部、国际科学与工程办公室以及数学和物理科学理事会多学科活动办公室的支持。

This Inter-American Materials Collaboration project examines the thermodynamic properties of thin films of magnetic compounds and liquid helium. The project brings together groups led by D. Landau, Center for Simulational Physics at the U. of Georgia in the US, and J.A. Plascak, at the Universidade Federal de Minas Gerais in Belo Horizonte, Brazil. The main issues addressed for the magnetic meso-structures are: i) how the lateral size of high quality magnetic nanofilm structures controls its magnetic properties; ii) the influence of atomic steps, islands, etc., on the magnetic behavior of such films; iii) the evolution of the thermodynamic behavior as a function of the film thickness. The studies of liquid helium focus on the use of classical "magnetic" models that are believed to be in the same universality class as helium. The computer simulations are done by using Monte Carlo methods for continuous spin systems together with re-weighting procedures and also spin dynamics for the intrinsic time evolution for the correlations. Computer simulations are of increasing importance due to their ability to determine the properties of many models in statistical physics that are not amenable to exact solution. The collaboration furthers the training in computer simulations and the international exposure of junior project participants. This award is supported by the Division of Materials Research, the Office of International Science and Engineering, and the Office of Multidisciplinary Activities in the Directorate for Mathematical and Physical Sciences.