Nernst effect
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Thermoelectric effect |
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In physics and chemistry, the Nernst effect (also termed first Nernst–Ettingshausen effect, after Walther Nernst and Albert von Ettingshausen) is a thermoelectric (or thermomagnetic) phenomenon observed when a sample allowing electrical conduction is subjected to a magnetic field and a temperature gradient normal (perpendicular) to each other. An electric field will be induced normal to both.
This effect is quantified by the Nernst coefficient |N|, which is defined to be
where is the of the electric field that results from the magnetic field's and the temperature gradient .
The reverse process is known as the Ettingshausen effect and also as the second Nernst–Ettingshausen effect.
Physical picture[]
Mobile energy carriers (for example conduction-band electrons in a semiconductor) will move along temperature gradients due to statistics and the relationship between temperature and kinetic energy. If there is a magnetic field transversal to the temperature gradient and the carriers are electrically charged, they experience a force perpendicular to their direction of motion (also the direction of the temperature gradient) and to the magnetic field. Thus, a perpendicular electric field is induced.
Sample types[]
Semiconductors exhibit the Nernst effect. This has been studied in the 1950s by Krylova, Mochan and many others. In metals however, it is almost non-existent. It appears in the vortex phase of type-II superconductors due to vortex motion. This has been studied by Huebener et al. High-temperature superconductors exhibit the Nernst effect both in the superconducting and in the pseudogap phase, as was first found by Xu et al. Heavy-Fermion superconductors can show a strong Nernst signal which is likely not due to the vortices, as was found by Bel et al.
See also[]
- Seebeck effect
- Peltier effect
- Hall effect
- Righi–Leduc effect
Journal articles[]
- R. P. Huebener and A. Seher, "Nernst Effect and Flux Flow in Superconductors. I. Niobium", Web
- R. P. Huebener and A. Seher, "Nernst Effect and Flux Flow in Superconductors. II. Lead Films", Web
- V. A. Rowe and R. P. Huebener, "Nernst Effect and Flux Flow in Superconductors. III. Films of Tin and Indium", Web
- Xu, Z. A.; Ong, N. P.; Wang, Y.; Kakeshita, T.; Uchida, S. (2000). "Vortex-like excitations and the onset of superconducting phase fluctuation in underdoped La2−xSrxCuO4". Nature. 406 (6795): 486–488. Bibcode:2000Natur.406..486X. doi:10.1038/35020016. PMID 10952303. S2CID 205007888.
- Bel, R.; Behnia, K.; Nakajima, Y.; Izawa, K.; Matsuda, Y.; Shishido, H.; Settai, R.; Onuki, Y. (2004). "Giant Nernst Effect in CeCoIn5". Physical Review Letters. 92 (21): 217002. arXiv:cond-mat/0311473. Bibcode:2004PhRvL..92u7002B. doi:10.1103/PhysRevLett.92.217002. PMID 15245310. S2CID 119337785.
- Krylova, T. V.; Mochan, I. V. (1955). J. Tech. Phys. (USSR). 25: 2119.
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(help) - Nernst effect on arxiv.org
- Walther Nernst
- Electrodynamics
- Thermoelectricity