Nevill Francis Mott

Nevill Francis Mott
Born	(1905-09-30)30 September 1905 Leeds, England
Died	8 August 1996(1996-08-08) (aged 90) Milton Keynes, Buckinghamshire, England
Nationality	United Kingdom
Fields	Physics
Institutions	University of Manchester Gonville and Caius College, Cambridge University of Bristol
Alma mater	St John's College, Cambridge
Doctoral advisor	R.H. Fowler
Notable awards	Nobel Prize in Physics (1977)

Sir Nevill Francis Mott, CH, FRS^[1] (30 September 1905 – 8 August 1996) was an English physicist who won the Nobel Prize for Physics in 1977 for his work on the electronic structure of magnetic and disordered systems, especially amorphous semiconductors. The award was shared with Philip W. Anderson and J. H. Van Vleck, who had pursued independent research. In 1981 his Nobel Award winning discovery was disproved by Gordon Thomas, T.F. Rosenbaum, K. Andres, and R.N. Bhatt, American physicists.^[2] In 1973 he was awarded the A. A. Griffith Medal and Prize.

Biography[edit]

Early years[edit]

Mott was born in Leeds to Lilian Mary Reynolds and Charles Francis Mott and grew up first in the village of Giggleswick, in the West Riding of Yorkshire, where his father was Senior Science Master at the local school. The family moved (due to his father's jobs) first to Staffordshire, then to Chester and finally Liverpool, where his father had been appointed Director of Education. Mott was at first educated at home by his mother, who was a Cambridge Mathematics Tripos graduate. His parents met in the Cavendish Laboratory, when both were engaged in physics research. At age ten, he began formal education at Clifton College in Bristol, then at St. John's College, Cambridge, where he read the Mathematics Tripos.

Career[edit]

Mott was appointed to a lecturership at the University of Manchester in 1929. He returned to Cambridge in 1930 as a Fellow and lecturer of Gonville and Caius College, and in 1933 moved to the University of Bristol as Melville Wills Professor in Theoretical Physics.

In 1948 he became Henry Overton Wills Professor of Physics and Director of the Henry Herbert Wills Physical Laboratory at Bristol. In 1954 he was appointed Cavendish Professor of Physics at Cambridge, a post he held until 1971. Additionally he served as Master of Gonville and Caius College, 1959-1966.

His early works were on the theoretical analysis of collisions in gases, notably the collision with spin flip of an electron against a H atom, which would stimulate works after le last war by André Blandin, the Kondo in Japan to study similar effects between conduction electrons and magnetic properties in metals. This sort of activity led him to writing two books: one with Sneddon giving a simple and clear description of quantum mechanics, with a emphasis on the Schroedinger equation in real space; the other with Marvey on atomic and electronic collisions in gases, using the rotational symmetry of electronic states in the Hartree Fock approximation.

But already in the middle of the 1930s, his interests had broadened toward solid states leading to two more books that would have a great impact on the development of the field before and after the war. In 1936 his book with H. Jones on the Theory of metals and alloys described a simplified framework which led to rapid progresses.

The concept of nearly free valence electrons in metallic alloys explained the special stability of the Hume-Rothery phases if the Fermi sphere of the sp valence electrons, treated as free, would be scattered by the Brillouin zone boundaries of the atomic structure. The description of the impurities in metals by the Thomas Fermi approximation would explain why such impurities would not interact at long range. Finally the delocalisation of the valence d electrons in transitional metals and alloys would explain the possibility for the magnetic atomic moments to be expressed as fractions of Bohr magnetons, leading to ferro or antiferromagnetic coupling at short range. This last contribution, produced at the first international conference on magnetism, held in Strasbourg in May 1939, reinforced similar points of view defended at the time in France by the future Nobel laureate Louis Néel. In 1949, Mott suggested to Jacques Friedel to use the approach developed in Mott and Marvey for a more accurate description of the screening of the impurity in a metal, leading to the characteristic long range charge oscillations. Friedel also used the concept developed in that book of virtual bound level to describe a situation when the atomic potential considered is not quite strong enough to create a (real) bound level of symmetry e ≠ o. The consequences of these remarks on the more exact approaches of cohesion in rp as well as d metals were mostly developed by his students in Orsay.

The second book, with Ronald Wilfred Gurney, on the Physical chemistry of solids was more diverse. It treated notably of the oxidation of metals at low temperatures, where it described the growth of the oxide layer as due to the electric field developed between the metal and absorbed oxygen ions, which could force the way of metallic or oxygen ions through a disordered oxide layer. The book also analyzed the photographic reactions in ionic silver compound in terms of precipitation of silver ions into metallic clusters.

If this second field had a direct and ion lasting consequence ion the research activity of John (Jack) Mitchell, in Bristol and in the USA (Mott's accomplishments include explaining theoretically the effect of light on a photographic emulsion (see latent image)) the oxidation work, besides fostering new work in the field, notably by J. Bénard an N. Cabrera in Paris, was the roots of the concept of the conduction gap produced in semiconductors by gradients in the distribution of donor and acceptor impurities.

When Mott returned to Bristol after his war work, notably on the role of plastic deformation on the progression of fracture cracks, his chance meeting and hiring of F. Charles Frank led both of them to develop, with the help of others such as Franck Nabarro and Alan H. Cottrell from Birmingham, to attack with the field of dislocations, in which Bristol shone with a new vigor, especially at the end of the 1940s. If Mott only produced early and somewhat minor contributions to that field, notably on alloy hardening with Nabarro and on the topology of a dislocation network lowering the apparent elastic constants of a crystal, there is no doubt that Mott's enthusiasm played its role in the three major steps forward in the field by F. C. Frank on crystal growth and plasticity and later, in Cambridge, by P. Hirsch on the thin film electron microscopy.

At the same time, however, Mott started playing around electron correlations and their possible role in Verwey's compounds such as nickel oxides which could switch from metals to insulators under various physical conditions (transition of substances from metallic to nonmetallic states (Mott transition)). The term Mott insulator is also named for him. With the analysis of disorders in covalent structures, they would provide a new book and the contributions invoked for the Nobel prize which seemed somewhat too long delayed.

He introduced Mott polynomials.

Mott was elected a Fellow of the Royal Society in 1936.^[1] Mott served as president of the Physical Society in 1957. In the early 1960s he was chairman of the British Pugwash group. He was knighted in 1962.^[3] He continued to work until he was about ninety. He was made a Companion of Honour in 1995.

Publications[edit]

N. F. Mott revived the old Philosophical Magazine and transformed it into a lively publication essentially centered on the then new field of solid state physics, which attracted writers, readers and general interest on a world scales. Having received from F. Seitz, the in Urbana USA, a very long paper on point defects in crystals, obviously too long for Phil. MAg., N. F. Mott decide to create a new publication, Advances in Physics for such review papers. Both publications are still active in 2013.

Personal life[edit]

Mott was married to Ruth Eleanor Horder, and had two daughters, Elizabeth and Alice. He died in Milton Keynes in Buckinghamshire.

Offices held[edit]

See also[edit]

• Mott-Gurney Law

Bibliography[edit]

• N. F. Mott, Metal-Insulator Transitions, second edition (Taylor & Francis, London, 1990). ISBN 0-85066-783-6, ISBN 978-0-85066-783-7
• N. F. Mott, A Life in Science, (Taylor & Francis, London, 1986). ISBN 0-85066-333-4, ISBN 978-0-85066-333-4
• Brian Pippard, Nevill Francis Mott, Physics Today, March 1997, pp. 95 and 96: (pdf).
• J. Friedel, direct quotation.

References[edit]

External links[edit]

• Delightful BBC video of 1985 interview with Nevill Mott (accessed Oct 8, 2010)
• Nobel lecture (PDF)
• Sir Nevill Francis Mott
• Mott's memories University of Bristol (accessed Jan 2006)
• National Cataloguing Unit for the Archives of Contemporary Scientists Bath University