Edmund Clifton Stoner
Encyclopedia
Edmund Clifton Stoner was a British
theoretical physicist
. He is principally known for his work on the origin and nature of itinerant ferromagnetism
(the type of ferromagnetic behavior associated with pure transition metals like cobalt, nickel, and iron), including the collective electron theory of ferromagnetism
and the Stoner criterion for ferromagnetism
.
(1911–1918) and then attended Cambridge University in 1918, matriculating in 1921. After graduation, he worked at the Cavendish Laboratory
on the absorption of X-rays by matter and electron
energy levels; his 1924 paper on this subject prefigured the Pauli exclusion principle
. He was then appointed as a lecturer at the University of Leeds
in 1924, and became a professor of theoretical physics there in 1939. He did some early work in astrophysics
and computed a limit for the mass of white dwarf stars in 1930. Most of his research, however, was on magnetism
, where, starting in 1938, he developed the collective electron theory of ferromagnetism
.
He retired in 1963. The E. C. Stoner building at the University of Leeds is named after him.,,
He was elected a Fellow of the Royal Society in May 1937
Stoner had been diagnosed with diabetes in 1919. He controlled it with diet until 1927, when insulin
treatment became available.
can spontaneously split into up and down spins. This happens if the relative gain in exchange interaction
(the interaction of electrons via the Pauli exclusion principle) is larger than the loss in kinetic energy.
where
is the energy of the metal before exchange effects are included, 
and 
are the energies of the spin up and down electron bands respectively. The Stoner parameter which is a measure of the strength of the exchange correlation is denoted 
, the number of electrons is 
. Finally 
is the wavenumber
as the electrons bands are in wavenumber-space. If more electrons favour one of the states this will create magnetism
. The electrons obey Fermi–Dirac statistics so if when the above formula's are summed over all
-space then a criterion for ferromagnetism can be established as
where
is the density of states
at the fermi energy
.
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
theoretical physicist
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...
. He is principally known for his work on the origin and nature of itinerant ferromagnetism
Magnetism
Magnetism is a property of materials that respond at an atomic or subatomic level to an applied magnetic field. Ferromagnetism is the strongest and most familiar type of magnetism. It is responsible for the behavior of permanent magnets, which produce their own persistent magnetic fields, as well...
(the type of ferromagnetic behavior associated with pure transition metals like cobalt, nickel, and iron), including the collective electron theory of ferromagnetism
Ferromagnetism
Ferromagnetism is the basic mechanism by which certain materials form permanent magnets, or are attracted to magnets. In physics, several different types of magnetism are distinguished...
and the Stoner criterion for ferromagnetism
Ferromagnetism
Ferromagnetism is the basic mechanism by which certain materials form permanent magnets, or are attracted to magnets. In physics, several different types of magnetism are distinguished...
.
Biography
Stoner born in Esher, Surrey, the son of cricketer Arthur Hallett Stoner. He won a scholarship to Bolton SchoolBolton School
Bolton School is an independent day school in Bolton, in the North-West of England. It comprises a co-educational Nursery and Infant School and single sex Junior and Senior Schools . With almost 2,400 pupils it is one of the largest independent day schools in the country.-History:Bolton School...
(1911–1918) and then attended Cambridge University in 1918, matriculating in 1921. After graduation, he worked at the Cavendish Laboratory
Cavendish Laboratory
The Cavendish Laboratory is the Department of Physics at the University of Cambridge, and is part of the university's School of Physical Sciences. It was opened in 1874 as a teaching laboratory....
on the absorption of X-rays by matter and electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
energy levels; his 1924 paper on this subject prefigured the Pauli exclusion principle
Pauli exclusion principle
The Pauli exclusion principle is the quantum mechanical principle that no two identical fermions may occupy the same quantum state simultaneously. A more rigorous statement is that the total wave function for two identical fermions is anti-symmetric with respect to exchange of the particles...
. He was then appointed as a lecturer at the University of Leeds
University of Leeds
The University of Leeds is a British Redbrick university located in the city of Leeds, West Yorkshire, England...
in 1924, and became a professor of theoretical physics there in 1939. He did some early work in astrophysics
Astrophysics
Astrophysics is the branch of astronomy that deals with the physics of the universe, including the physical properties of celestial objects, as well as their interactions and behavior...
and computed a limit for the mass of white dwarf stars in 1930. Most of his research, however, was on magnetism
Magnetism
Magnetism is a property of materials that respond at an atomic or subatomic level to an applied magnetic field. Ferromagnetism is the strongest and most familiar type of magnetism. It is responsible for the behavior of permanent magnets, which produce their own persistent magnetic fields, as well...
, where, starting in 1938, he developed the collective electron theory of ferromagnetism
Ferromagnetism
Ferromagnetism is the basic mechanism by which certain materials form permanent magnets, or are attracted to magnets. In physics, several different types of magnetism are distinguished...
.
He retired in 1963. The E. C. Stoner building at the University of Leeds is named after him.,,
He was elected a Fellow of the Royal Society in May 1937
Stoner had been diagnosed with diabetes in 1919. He controlled it with diet until 1927, when insulin
Insulin
Insulin is a hormone central to regulating carbohydrate and fat metabolism in the body. Insulin causes cells in the liver, muscle, and fat tissue to take up glucose from the blood, storing it as glycogen in the liver and muscle....
treatment became available.
Stoner model of ferromagnetism
Electron bandsElectronic band structure
In solid-state physics, the electronic band structure of a solid describes those ranges of energy an electron is "forbidden" or "allowed" to have. Band structure derives from the diffraction of the quantum mechanical electron waves in a periodic crystal lattice with a specific crystal system and...
can spontaneously split into up and down spins. This happens if the relative gain in exchange interaction
Exchange interaction
In physics, the exchange interaction is a quantum mechanical effect without classical analog which increases or decreases the expectation value of the energy or distance between two or more identical particles when their wave functions overlap...
(the interaction of electrons via the Pauli exclusion principle) is larger than the loss in kinetic energy.
where
is the energy of the metal before exchange effects are included, and are the energies of the spin up and down electron bands respectively. The Stoner parameter which is a measure of the strength of the exchange correlation is denoted , the number of electrons is . Finally is the wavenumberWavenumber
In the physical sciences, the wavenumber is a property of a wave, its spatial frequency, that is proportional to the reciprocal of the wavelength. It is also the magnitude of the wave vector...
as the electrons bands are in wavenumber-space. If more electrons favour one of the states this will create magnetism
Magnetism
Magnetism is a property of materials that respond at an atomic or subatomic level to an applied magnetic field. Ferromagnetism is the strongest and most familiar type of magnetism. It is responsible for the behavior of permanent magnets, which produce their own persistent magnetic fields, as well...
. The electrons obey Fermi–Dirac statistics so if when the above formula's are summed over all
-space then a criterion for ferromagnetism can be established aswhere
is the density of statesDensity of states
In solid-state and condensed matter physics, the density of states of a system describes the number of states per interval of energy at each energy level that are available to be occupied by electrons. Unlike isolated systems, like atoms or molecules in gas phase, the density distributions are not...
at the fermi energy
Fermi energy
The Fermi energy is a concept in quantum mechanics usually referring to the energy of the highest occupied quantum state in a system of fermions at absolute zero temperature....
.
Selected publications
- The distribution of electrons among atomic levels, Philosophical Magazine (6th series) 48 (1924), pp. 719–736.
- The limiting density of white dwarf stars, Philosophical Magazine (7th series) 7 (1929), pp. 63–70.
- The equilibrium of dense stars, Philosophical Magazine (7th series) 9 (1930), pp. 944–963.
- Magnetism and atomic structure, London: Methuen, 1926.
- Magnetism and matter, London: Methuen, 1934.
- Collective electron ferromagnetism, Proceedings of the Royal Society of London, series A, 165 (1938), pp. 372–414.
- Collective electron ferromagnetism II. Energy and specific heat, Proceedings of the Royal Society of London, series A, 169 (1939), pp. 339–371.
- Collective electron ferromagnetism in metals and alloys, Journal de physique et le radium (8th series) 12 (1951), pp. 372–388.