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

초록

The electronic structures of Gd-substituted Bi<inf>2−x</inf>Gd<inf>x</inf>Te<inf>3</inf> 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<inf>2−x</inf>Gd<inf>x</inf>Te<inf>3</inf> crystals. The measured Gd 3d 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 5p and Bi 6p states. A good agreement is found between the measured VB PES spectra of Bi<inf>2−x</inf>Gd<inf>x</inf>Te<inf>3</inf> and the calculated partial densities of states, revealing that the Te 5p states will play an important role in determining the thermoelectric and topological properties of Bi<inf>2−x</inf>Gd<inf>x</inf>Te<inf>3</inf>. © 2018 Elsevier B.V.

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