2014/03/30 by Jan Rusz, Somnath Bhowmick, Mattias Eriksson +1 · 1 citation
Physics and Astronomy · #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevb.89.134428
13 pages, 12 figures, submitted. arXiv admin note: text overlap with arXiv:1304.5461
arxiv created 2014/03/30 · arxiv updated 2015/06/19
Use of electron vortex beams (EVB), that is convergent electron beams carrying an orbital angular momentum (OAM), is a novel development in the field of transmission electron microscopy. They should allow measurement of element-specific magnetic properties of thin crystals using electron magnetic circular dichroism (EMCD)---a phenomenon similar to the x-ray magnetic circular dichroism. Recently it has been shown computationally that EVBs can detect magnetic signal in a scanning mode only at atomic resolution. In this follow-up work we explore in detail the elastic and inelastic scattering properties of EVBs on crystals, as a function of beam diameter, initial OAM, acceleration voltage and beam displacement from an atomic column. We suggest that for a 10 nm layer of bcc iron oriented along (001) zone axis an optimal configuration for a detection of EMCD is an EVB with OAM of 1ℏ and a diameter of 1.6 Å, acceleration voltage 200 keV and an annular detector with inner and outer diameters of G and 5G, respectively, where G=(100).