期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 109, 期 9, 页码 3243-3246出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1118371109
关键词
strongly correlated electrons; Kondo insulator; metal-insulator transitions; electronic structure; material science
资金
- National Science Foundation (NSF) materials world network [NSF DMR 0806937, NSF DMR 0906941]
- Partner University
- American Chemical Society [48802]
- Division Of Materials Research
- Direct For Mathematical & Physical Scien [0906943, 0806937] Funding Source: National Science Foundation
The intermetallic FeSi exhibits an unusual temperature dependence in its electronic and magnetic degrees of freedom, epitomized by the cross-over from a low-temperature nonmagnetic semiconductor to a high-temperature paramagnetic metal with a Curie-Weiss-like susceptibility. Many proposals for this unconventional behavior have been advanced, yet a consensus remains elusive. Using realistic many-body calculations, we here reproduce the signatures of the metal-insulator cross-over in various observables: the spectral function, the optical conductivity, the spin susceptibility, and the Seebeck coefficient. Validated by quantitative agreement with experiment, we then address the underlying microscopic picture. We propose a new scenario in which FeSi is a band insulator at low temperatures and is metalized with increasing temperature through correlation induced incoherence. We explain that the emergent incoherence is linked to the unlocking of iron fluctuating moments, which are almost temperature independent at short timescales. Finally, we make explicit suggestions for improving the thermoelectric performance of FeSi based systems.
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