Unveiling the electronic transformations in the semi-metallic correlated-electron transitional oxide Mo8O23.
Sci Rep
; 9(1): 15959, 2019 Nov 04.
Article
en En
| MEDLINE
| ID: mdl-31685868
ABSTRACT
Mo8O23 is a low-dimensional chemically robust transition metal oxide coming from a prospective family of functional materials, MoO3-x, ranging from a wide gap insulator (x = 0) to a metal (x = 1). The large number of stoichometric compounds with intermediate x have widely different properties. In Mo8O23, an unusual charge density wave transition has been suggested to occur above room temperature, but its low temperature behaviour is particularly enigmatic. We present a comprehensive experimental study of the electronic structure associated with various ordering phenomena in this compound, complemented by theory. Density-functional theory (DFT) calculations reveal a cross-over from a semi-metal with vanishing band overlap to narrow-gap semiconductor behaviour with decreasing temperature. A buried Dirac crossing at the zone boundary is confirmed by angle-resolved photoemission spectroscopy (ARPES). Tunnelling spectroscopy (STS) reveals a gradual gap opening corresponding to a metal-to-insulator transition at 343 K in resistivity, consistent with CDW formation and DFT results, but with large non-thermal smearing of the spectra implying strong carrier scattering. At low temperatures, the CDW picture is negated by the observation of a metallic Hall contribution, a non-trivial gap structure in STS below â¼170 K and ARPES spectra, that together represent evidence for the onset of the correlated state at 70 K and the rapid increase of gap size below â¼30 K. The intricate interplay between electronic correlations and the presence of multiple narrow bands near the Fermi level set the stage for metastability and suggest suitability for memristor applications.
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1
Colección:
01-internacional
Base de datos:
MEDLINE
Tipo de estudio:
Clinical_trials
Idioma:
En
Revista:
Sci Rep
Año:
2019
Tipo del documento:
Article
País de afiliación:
Eslovenia