Open AccessA versatile X‐ray phase retarder for lock‐in XMCD measurements
Author(s) -
Poldi Eduardo H. T.,
Escanhoela Jr Carlos A.,
Fonseca Jr Jairo,
Eleotério Marcos A. S.,
dos Reis Ricardo D.,
Lang Jonathan C.,
Haskel Daniel,
Souza-Neto Narcizo M.
Publication year - 2020
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s1600577520009558
Subject(s) - magnetic circular dichroism , optics , circular polarization , x ray magnetic circular dichroism , physics , helicity , polarization (electrochemistry) , magnetometer , materials science , magnetic field , chemistry , particle physics , quantum mechanics , astronomy , spectral line , microstrip
X‐ray magnetic circular dichroism (XMCD) is a technique commonly used to probe magnetic properties of materials with element and orbital selectivity, which requires the use of circularly polarized (CP) X‐rays. It is possible to accomplish XMCD experiments with fixed CP and alternating the magnetic field orientation, but most reliable data are obtained when alternating the magnetization orientation and the polarization between right and left helicities. A versatile strategy has been developed to perform XMCD experiments using a hard X‐ray quarter‐wave plate, at both polychromatic dispersive and conventional monochromatic optics, in combination with synchronous data acquisition. The switching frequency waveform is fed into a lock‐in amplifier to detect and amplify the XMCD signal. The results on a reference sample demonstrate an improvement in data quality and acquisition time. The instrumentation successfully generated 98% of CP X‐rays switching the beam helicity at 13 Hz, with the possibility of faster helicity switching once it is installed at the new Brazilian fourth‐generation source, SIRIUS.