Advanced Photon Source

A U.S. Department of Energy, Office of Science,
Office of Basic Energy Sciences national synchrotron x-ray research facility

 

Partner User Proposal Abstract

Enhanced Sensitivity of X-ray Magnetic Circular Dichroism Measurements Using Phase Lock-in Detection (PUP-7)

We propose to develop a phase lock detection system on beamline 4-ID-D for measuring extremely small x-ray magnetic circular dichroism (XMCD) signals. The ability to acquire small XMCD spectra has become essential in order to address problems of current scientific interest, such as, detecting small induced moments at magnetic/non-magnetic interfaces or probing local magnetism using helicity dependent XAFS. Measuring XMCD signals smaller than ~10^-3, however, is difficult using conventional techniques because systematic errors in the data collection process are the dominant source of uncertainty in the measured spectra. Using phase lock-in techniques, though, we can overcome these limitations and extend our sensitivity to signals as small as ~10-6. This will significantly enhance the capabilities of 4-ID-D, with the potential to increase the user community served by this beamline.