Electronic structure of a thermoelectric material: BiCuSO

Abstract

We investigate transport properties and the electronic structure of BiCuSO, a thermoelectric material which was predicted as a possible parent compound for unconventional superconductivity. For the p-type BiCuSO samples studied in this paper, our transport measurements show metallic behavior down to 2 K, and we observe an increase of saturated magnetic moment around 4 K, which could be due to the reorientation of the magnetic easy axis. Using angle-resolved photoemission spectroscopy measurements, we acquired the comprehensive electronic structure of BiCuSO including the predicted flat band, and by carrying out photon polarization dependent measurements we further investigated the orbital characters of bands near the Fermi level. Compared with its sister compound, BiCuSeO, we find the flat band could be the origin of high figure of merit (ZT ) value in the BiCuChO (Ch = S, Se) family.

Bulk Superlattice Analogues for Energy Conversion

“…The ionic interlayer interaction hinders the release of these trapped charges into the conductive [Cu 2 Se 2 ] 2– sublayers to become conduction carriers, making the superlattice structure disfavor fine electrical conductivity with an ∼0.8 eV indirect band gap. Recently, angle resolved photoemission spectroscopy (ARPES) confirmed that the unique valence band structure, a coexistence of light and heavy bands along the [110] and [100] directions, respectively, is suggested to be the origin of the large Seebeck coefficient and increased electrical conductivity in the hole-doped sample (Figure b). Thus, to obtain p-doped samples, substituting Bi 3+ by a divalent ion (Sr 2+ , Ca 2+ , Pb 2+ , etc.…”

“…(a) is adapted with permission from ref , copyright 2016 Wiley-VCH. (b) is adapted with permission from ref , copyright 2021 American Physical Society. (c) and (d) are adapted with permission from ref , copyright 2017 Royal Society of Chemistry.…”