SSCU Student Seminar
Name: Mr. Aditya Deo
Title: X-Ray Magnetic Circular Dichroism: Probing Spin and Orbital Magnetic Moments in Magnetic Materials
Date & Time: Thursday, 20th August 2026 at 4.00 p.m.
Venue: Rajarshi Bhattacharyya Memorial Lecture Hall, Chemical Sciences Building
Abstract:
Understanding the electronic and magnetic properties of materials requires probes that can provide element-specific information about their local electronic states and magnetic moments. Conventional magnetic characterization techniques generally provide macroscopic information, making it challenging to directly distinguish the contributions of individual elements to the magnetic response. X-ray absorption spectroscopy (XAS) provides an element-specific probe of the unoccupied electronic states through core-level excitations, while the use of circularly polarized X-rays introduces sensitivity to the magnetic state of the material.
In this seminar, I will introduce the principles of X-ray Magnetic Circular Dichroism (XMCD), which measures the difference in X-ray absorption for opposite photon helicities in the presence of a magnetic field. The origin of XMCD will be discussed in terms of X-ray absorption, electric-dipole selection rules, and circular polarization, followed by an overview of the experimental requirements and detection modes, including total electron yield, total fluorescence yield, transmission, and photoelectron yield. The two-step excitation and detection process underlying XMCD measurements will also be discussed. Particular emphasis will be placed on the orbital and spin magnetic-moment sum rules, which enable quantitative extraction of element-specific orbital and spin moments. The seminar will further highlight XMCD applications in magnetic materials, including studies of magnetic anisotropy and low-dimensional magnetic systems. Finally, experimental limitations along with future prospects of XMCD for investigating complex magnetic materials will be discussed.
References:
Vaz, C. A. F., van der Laan, G., Cavill, S. A., et al., “X-ray magnetic circular dichroism.” Nature Reviews Methods Primer, 5, 27 (2025).
J. Stöhr, H. A. Padmore, S. Anders, T. Stammler, and M. R. Scheinfein, “Principles of X-Ray Magnetic Dichroism Spectromicroscopy,” Surface Review and Letters 5, No. 6, 1297–1308 (1998).
van der Laan, G., & Figueroa, A. I., “X-ray magnetic circular dichroism—A versatile tool to study magnetism”. Coordination Chemistry Reviews, 277–278, 95–129 (2014).