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On the Lorenz number of multiband materials
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Thesberg, Mischa, Kosina, Hans and Neophytou, Neophytos (2017) On the Lorenz number of multiband materials. Physical Review B (Condensed Matter and Materials Physics), 95 (12). 125206. doi:10.1103/PhysRevB.95.125206
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WRAP-Lorenz-number-multiband-materials-Neophytou-2017.pdf - Accepted Version - Requires a PDF viewer. Download (810Kb) | Preview |
Official URL: http://dx.doi.org/10.1103/PhysRevB.95.125206
Abstract
There are many exotic scenarios where the Lorenz number of the Wiedemann-Franz law is known to deviate from expected values. However, in conventional semiconductor systems, it is assumed to vary between the values of ∼1.49×10−8WΩK−2 for nondegenerate semiconductors and ∼2.45×10−8WΩK−2 for degenerate semiconductors or metals. Knowledge of the Lorenz number is important in many situations, such as in the design of thermoelectric materials and in the experimental determination of the lattice thermal conductivity. Here, we show that, even in the simple case of two- and three-band semiconductors, it is possible to obtain substantial deviations of a factor of 2 (or in the case of a bipolar system with a Fermi level near the midgap, even orders of magnitude) from expectation. In addition to identifying the sources of deviation in unipolar and bipolar two-band systems, a number of analytical expressions useful for quantifying the size of the effect are derived. As representative case studies, a three-band model of the materials of lead telluride (PbTe) and tin sellenide (SnSe), which are important thermoelectric materials, is also developed and the size of possible Lorenz number variations in these materials explored. Thus, the consequence of multiband effects on the Lorenz number of real systems is demonstrated.
| Item Type: | Journal Article | ||||||
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| Subjects: | Q Science > QC Physics T Technology > TK Electrical engineering. Electronics Nuclear engineering |
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| Divisions: | Faculty of Science > Physics | ||||||
| Library of Congress Subject Headings (LCSH): | Semiconductors , Thermal conductivity, Nanostructures, Thermoelectric materials | ||||||
| Journal or Publication Title: | Physical Review B (Condensed Matter and Materials Physics) | ||||||
| Publisher: | American Physical Society | ||||||
| ISSN: | 1098-0121 | ||||||
| Official Date: | 31 March 2017 | ||||||
| Dates: |
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| Volume: | 95 | ||||||
| Number: | 12 | ||||||
| Article Number: | 125206 | ||||||
| DOI: | 10.1103/PhysRevB.95.125206 | ||||||
| Status: | Peer Reviewed | ||||||
| Publication Status: | Published | ||||||
| Access rights to Published version: | Restricted or Subscription Access | ||||||
| Funder: | Österreichische Forschungsförderungsgesellschaft (FFG), European Research Council (ERC), Horizon 2020 (European Commission) (H2020) | ||||||
| Grant number: | Project No. 850743 QTSMoS (FFG), Grant Agreement No. 678763 (H2020) |
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