An X-ray standing wave study of the diluted magnetic semiconductor Ga(Mn)As

We have combined the recently developed techniques of soft x-ray standing-wave angle-resolved photoemission (SW-ARPES) [Gray et al., EPL 104, 17004 (2013)] and hard x-ray ARPES (HARPES) [Gray et al., Nature Mat. 11, 957 (2012)] so as to be able to use single-crystal Bragg reflection to create the SW [Thiess et al., Sol. St. Comm. 150, 553 (2010)], thus permitting the first measurements of momentum- and element- resolved bulk electronic structure. The strengths of the SW-HARPES method are demonstrated using the dilute magnetic semiconductor Ga$_{(1-x)}$Mn$_x$As. A strong SW is generated by Bragg reflection of ca. 3 keV x-rays from the (111) planes of both undoped GaAs and Mn-doped thin films with x=0.05. Due to the uneven occupancy of (111) planes by either Ga(Mn) or As atoms, the element-specific band structure can be obtained with a help of the SW modulation in core levels. Apart from the site specific decomposition of the electronic structure, the SW measurements also confirmed a substitutional presence of Mn atoms at the Ga sites. This technique should be applicable to a broad range of complex materials.