Investigation of the Magnetic Anistropy and Magnetic Phase Transition using Stepped Surfaces

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Qiu 9805222 This is a fundamental research project in the field of magnetism. The research is focused on the properties of artificially structured thin magnetic films. The objective is an understanding of the role of lattice symmetry-breaking on the magnetic anisotropy in these materials. The magnetic anisotropy is a major determinant of the magnetic properties of the materials, particularly there properties as candidates for magnetic storage media. Nanometer-sized atomic steps on a controlled surface will be created to break the four-fold rotation symmetry to induce a uniaxial magnetic anisotropy within the film plane. This step- induced magnetic anisotropy and its effect on the two-dimensional (2D) magnetic phase transition will be investigated systematically as a function of the step-density. A novel aspect of the project is to employ a curved substrate as a possible means of controlling the step-density in a continuous way. All samples will be grown by Molecular Beam Epitaxy (MBE) and characterized by Reflection High-Energy Electron Diffraction (RHEED), Low-Energy Electron Diffraction (LEED), Auger Electron spectroscopy (AES) and Scanning Tunneling Microscopy (STM). The magnetic properties of the films will be measured in situ by Surface Magneto-Optic Kerr Effect (SMOKE) technique. %%% This is a fundamental research project in the field of magnetism. Rapid development in the information storage technology demands an understanding of the magnetic behavior of materials at the atomic scale. The goal of this proposal is to gain a deeper understanding on how the magnetic anisotropy of a magnet will be affected by limiting the size of the magnetic at the atomic scale. To realize this goal, well-defined atomic steps will be used to break the rotation symmetry of the continuous surface. The step induced magnetic anisotropy and its effect on the 2D magnetic pha se transition will then be systematically investigated as a function of the step-density. State-of-the-art techniques such as the Molecular Beam Epitaxy (MBE) and Scanning Tunneling Microscopy (STM) will be applied to this project to fabricate and characterize the thin films at the atomic scale. Success of this project will be important not only to the understanding of two-dimensional magnetism, but also to the development of new magnetic devices for practical applications. ***