In physics and chemistry, the Nernst effect (also termed first Nernst–Ettingshausen effect, after

Walther Nernst Walther Hermann Nernst (; 25 June 1864 – 18 November 1941) was a German chemist known for his work in thermodynamics, physical chemistry, electrochemistry, and solid state physics. His formulation of the Nernst heat theorem helped pave the wa ...

and

Albert von Ettingshausen Albert von Ettingshausen (30 March 1850 – 9 June 1932) was an Austrian physicist. He was professor of physics at Graz University of Technology, where he also taught electrical engineering. Earlier he was an assistant to Ludwig Boltzmann at the U ...

) is a

thermoelectric The thermoelectric effect is the direct conversion of temperature differences to electric voltage and vice versa via a thermocouple. A thermoelectric device creates a voltage when there is a different temperature on each side. Conversely, when ...

(or thermomagnetic) phenomenon observed when a sample allowing

electrical conduction Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric current. A low resistivity indicates a material that readily allows ...

is subjected to a

magnetic field A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...

and a temperature gradient normal (perpendicular) to each other. An

electric field An electric field (sometimes E-field) is the physical field that surrounds electrically charged particles and exerts force on all other charged particles in the field, either attracting or repelling them. It also refers to the physical field fo ...

will be induced normal to both. This effect is quantified by the Nernst coefficient , ''N'', , which is defined to be ::

, N, =\frac

where

E_Y

is the y-component of the electric field that results from the magnetic field's z-component

B_Z

and the temperature gradient

dT/dx

. The reverse process is known as the

Ettingshausen effect The Ettingshausen effect (named for Albert von Ettingshausen) is a thermoelectric (or thermomagnetic) phenomenon that affects the electric current in a conductor when a magnetic field is present. Ettingshausen and his PhD student Walther Nernst w ...

and also as the second Nernst–Ettingshausen effect.

Physical picture

Mobile Mobile may refer to: Places * Mobile, Alabama, a U.S. port city * Mobile County, Alabama * Mobile, Arizona, a small town near Phoenix, U.S. * Mobile, Newfoundland and Labrador Arts, entertainment, and media Music Groups and labels * Mobile ( ...

energy carriers (for example conduction-band

electron The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no kn ...

s in a

semiconductor A semiconductor is a material which has an electrical resistivity and conductivity, electrical conductivity value falling between that of a electrical conductor, conductor, such as copper, and an insulator (electricity), insulator, such as glas ...

) will move along

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...

gradients due to statistics and the relationship between temperature and kinetic energy. If there is a

transversal to the temperature gradient and the carriers are

electrically charged Electric charge is the physical property of matter that causes charged matter to experience a force when placed in an electromagnetic field. Electric charge can be ''positive'' or ''negative'' (commonly carried by protons and electrons respe ...

, they experience a

force In physics, a force is an influence that can change the motion of an object. A force can cause an object with mass to change its velocity (e.g. moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a p ...

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

metal A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typicall ...

s 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.

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
* * *{{Cite journal , last1=Krylova , first1=T. V. , last2=Mochan , first2=I. V. , journal=J. Tech. Phys. (USSR) , volume=25 , pages=2119 , year=1955 Walther Nernst Electrodynamics Thermoelectricity

Physical picture

Sample types

See also

Journal articles