A versatile X-ray phase retarder for lock-in XMCD measurements

Autor(es)

Poldi, Eduardo H. T. ; Escanhoela Jr, Carlos A. ; Fonseca Jr, Jairo ; Eleoterio, Marcos A. S. ; dos Reis, Ricardo D. ; Lang, Jonathan C. ; Haskel, Daniel ; Souza-Neto, Narcizo M.

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF SYNCHROTRON RADIATION; v. 27, p. 7-pg., 2020-09-01.

Resumo

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. (AU)

• Processo FAPESP: 14/26620-8 - Lâmina 1/4 de onda de Raios X para dicroísmo magnético
• Beneficiário: Eduardo Henrique de Toledo Poldi
• Modalidade de apoio: Bolsas no Brasil - Iniciação Científica
• Processo FAPESP: 14/05480-3 - EMU concedido no processo 2013/22436-5: instalação para experimentos em altas pressões
• Beneficiário: Narcizo Marques de Souza Neto
• Modalidade de apoio: Auxílio à Pesquisa - Programa Equipamentos Multiusuários
• Processo FAPESP: 14/26450-5 - Magnetismo orbital em perovskitas dublas sob condições extremas por técnicas de radiação síncrotron
• Beneficiário: Carlos Augusto Escanhoela Júnior
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 13/22436-5 - Técnicas de Luz Síncrotron sob condições extremas
• Beneficiário: Narcizo Marques de Souza Neto
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores