MALTS: A tool to simulate Lorentz Transmission Electron Microscopy from micromagnetic simulations

摘要

Here we describe the development of the MALTS software which is a generalisedtool that simulates Lorentz Transmission Electron Microscopy (LTEM) contrast ofthin magnetic nanostructures. Complex magnetic nanostructures typically havemultiple stable domain structures. MALTS works in conjunction with the openaccess micromagnetic software Object Oriented Micromagnetic Framework or MuMax.Magnetically stable trial magnetisation states of the object of interest areinput into MALTS and simulated LTEM images are output. MALTS computes themagnetic and electric phases accrued by the transmitted electrons via theAharonov-Bohm expressions. Transfer and envelope functions are used to simulatethe progression of the electron wave through the microscope lenses. The finalcontrast image due to these effects is determined by Fourier Optics. Similarapproaches have been used previously for simulations of specific cases of LTEMcontrast. The novelty here is the integration with micromagnetic codes via asimple user interface enabling the computation of the contrast from anystructure. The output from MALTS is in good agreement with both experimentaldata and published LTEM simulations. A widely-available generalized code forthe analysis of Lorentz contrast addresses is a much needed step towards theuse of LTEM as a standardized laboratory technique.