Phase contrast of spherical magnetic particles

作     者：M. DE GRAEF N. T. NUHFER M. R. McCARTNEY 

作者机构：Department of Materials Science and Engineering Carnegie Mellon University Pittsburgh PA 15213-3890 U.S.A. Center for Solid State Science Arizona State University Tempe AZ 85287 U.S.A. 

出 版 物：《Journal of Microscopy》 

年 卷 期：2001年第194卷第1期

学科分类：07[理学] 08[工学] 

主　　题：Lorentz microscopy magnetic particles electron holography 

摘      要：This paper derives analytical expressions for the magnetic and electrostatic phase shifts of a plane electron wave upon traversing a spherical, uniformly magnetized particle with a non-zero mean inner potential. The Aharonov—Bohm phase shift is represented in terms of dimensionless parameters. Standard Foucault and Fresnel Lorentz image simulations are presented for a range of particle sizes and saturation inductions. We discuss the detection limits of the Lorentz techniques and compare them with the sensitivity of the electron holography method. We conclude the paper with experimental holography results for nanocrystalline cobalt particles; the observed phase changes are in good agreement with the analytical predictions.