Development of sub-nanometer resolution depth-resolved XAFS/XMCD in the soft x-ray region towards operando measurements

Recent development of the depth-resolved X-ray absorption fine structure (XAFS) and X-ray magnetic circular dichro-ism (XMCD) techniques in the soft X-ray region is presented. A sub-nanometer resolution in the XAFS XMCD measurement is achieved by collecting the Auger electrons at di erent detection angles, which correspond to di erent probing depths, but it is impossible to apply this technique under magnetic and or electric fields because the electron trajectory is a ected by the external fields. By adopting the fluorescence-yield detection mode using a soft X-ray CCD camera, the depth-resolved XAFS XMCD tech-nique under the external fields is realized, which leads to the operando measurements for the chemical and magnetic states at the surface and interface. The depth-resolved XAFS XMCD measurement for an FeCo film under the magnetic field is demonstrated for the first time, which suggests that the ∼15 ML-thick surface region consists of ∼60% oxides with little magnetization.