Analysis of Spin Polarized Transfer and of Micro-Macro Theories for Polymers and Liquid Crystals

University Of California-Santa Barbara, Santa Barbara CA

Investigators

Abstract

The investigator takes up three projects. In the first project, the emphasis is the analysis and the design of efficient numerical methods for the simulation of recent models proposed for the dynamics of the magnetization coupled to the spin accumulation in multilayers when a current perpendicular to the plane of the layers is applied. The dynamical equation for the spin is a diffusion equation with discontinuous coefficients, and the magnetization dynamics is described by the Landau-Lifshitz equation from ferromagnetism. In the second project, the investigator studies a new model for liquid crystals based on Inhomogeneous Density Functional Theory. The model can describe the isotropic, nematic, smectic A, and crystalline phases. Finally, in the third project, the investigator studies the formation of aggregates in polymer mixtures. Ferromagnetic materials are widely used in the magnetic recording industry, which continues to be the dominant technology for the storage of digital data. The project addresses some of the technological difficulties found in the design of magnetic devices such as magnetic memories (MRAMs). Liquid crystals have a wide range of applications. Their optical properties are highly sensitive to electric and magnetic fields, which has made liquid crystals ideal candidates for optical-switching devices, such as video displays and optical memories. They are very sensitive to temperature changes as well, which makes them useful in applications involving sensors. More generally, polymers appear in most aspects of our life, from the amniotic fluid inside biological cells, to plastics and shampoos used on a daily basis. Understanding the dynamics of biological membranes and transport through them is of fundamental importance in the development of efficient methods for the delivery of medicines. Understanding the process of aggregation in polymer mixtures can have a significant impact in the design of new products. This study of polymers and liquid crystals addresses some of these technological and biological issues.