Photoemission and soft X-ray absorption spectroscopy study of Gd-substituted thermoelectric and topological Bi2Te3

Abstract The electronic structures of Gd-substituted Bi 2− x Gd x Te 3 single crystals have been investigated by employing synchrotron-radiation spectroscopies, such as soft X-ray absorption spectroscopy (XAS), soft X-ray magnetic circular dichroism (XMCD), photoemission spectroscopy (PES), and scanning photoelectron microscopy (SPEM). SPEM measurements confirm that Gd ions are substituted homogeneously in Bi 2− x Gd x Te 3 crystals. The measured Gd 3 d XAS and XMCD spectra provide evidence that the substituted Gd ions are trivalent and magnetic. The hν -dependence of the valence-band (VB) PES spectra are described well by the hν -dependent contributions of the Te 5 p and Bi 6 p states. A good agreement is found between the measured VB PES spectra of Bi 2− x Gd x Te 3 and the calculated partial densities of states, revealing that the Te 5 p states will play an important role in determining the thermoelectric and topological properties of Bi 2− x Gd x Te 3 .