Departamento de Física

Facultad de Ciencia
Universidad de Santiago de Chile

Seminario de Física (extra) - Lunes 24 de Septiembre - 2:30pm - Rudolf Schaefer

Fecha: 
09/24/2018 - 11:00
Título: "Micromagnetism, Magnetic Microstructure and their Magneto-Optical Analysis"
 
Dr. Rudolf Schaefer del Leibniz Institute for Solid State and Materials Research (IFW) Dresden, Germany
 
Abstract: The characterization of magnetic materials in research and development usually relies on the measurement of hysteresis curves, which are determined by the magnetic microstructure of the material. The knowledge of magnetic domains and their substructures is therefore essential for the interpretation of magnetization curves.
Magneto-optical microscopy, in particular Kerr microscopy, is just one among many techniques to image domains and processes, and it may be considered a "classical“ method (compared to „modern“ magnetic microscopy based, for instance, on circular X-ray dichroism or spin-polarized tunneling). Nevertheless, it is the most flexible and versatile technique and due to substantial technical progress in recent time magneto-optical domain imaging becomes very powerful again.

In this presentation, a review will be given on the possibilities and recent developments of magnetic domain imaging by wide-field magneto-optical microscopy. Besides some basics, this includes depth-sensitive and time-resolved domain imaging, a mathematical deconvolution method to enhance the lateral resolution, and on the other hand an overview imaging tool to maximize the field of view. Novel light-emitting diode (LED) lamps allow for contrast separation and -enhancement, vector magnetometry and in-situ quantitative Kerr microscopy of complete magnetization processes, as will be demonstrated on magnetic film and bulk materials.

By using magneto-optic indicator films (MOIF) with perpendicular or in-plane anisotropy, it is possible to image magnetic poles by Faraday microscopy. With the MOIF technique domain information can be obtained in cases where the sample surface is coated like on electrical steel. By using perpendicular MOIF films the domain contrast is even strong enough to allow for single-shot time-resolved imaging of coated transformer steel up to power frequencies. MOIF films also provide the potential to investigate the role of grain boundaries for flux propagation in such material.
 

Lunes 24 de septiembre del 2018 a las 14:30 hrs.

Sala de Conferencias, 3er Piso

Departamento de Física

Universidad de Santiago de Chile

 

Carrera: 
Doctorado en Ciencia con Mención en Física