Metal-insulator Mott transition

The system undergoes a metal-insulator Mott transition. 

N. F. Mott, Metal-Insulator Phase Transitions, Taylor and Francis, London, 1974. 

By adsorption of metal atoms, one can induce various reconstructed surfaces that show metal-insulator phase transitions. Some transitions apparently are of the Mott type [73], whereas the driving mechanism of others is still subject to discussion, particularly considering the role of defects. Glasslike, disordered states have been found, which are very similar to theoretical predictions for phase separation in correlated electron systems [105]. 

F. Gebhard, The Mott Metal-Insulator Transition- Models and Methods, Tracts in Modern Physics, 137, Springer (1997). 

Hubbard (13) elucidated a mathematical description of the change from one situation to another for the simplest case of a half-filled s band of a solid. His result is shown in Figure 11. For ratios of W/U greater than the critical value of 2/ /3 then a Fermi surface should be found and the system can be a metal. This critical point is associated with the Mott transition from metal to insulator. At smaller values than this parameter, then, a correlation, or Hubbard, gap exists and the system is an antiferromagnetic insulator. Both the undoped 2-1 -4 compound and the nickel analog of the one dimensional platinum chain are systems of this type. At the far left-hand side of Figure 11 we show pictorially the orbital occupancy of the upper and lower Hubbard bands. 

Mott, N. F. (1974) Metal-Insulator Transitions, Taylor Francis, London. 

The present author (Mott 1949, 1956, 1961) described a metal-insulator transition by imagining a crystalline array of hydrogen-like atoms with a lattice constant a that could be varied. The example of nickel oxide suggested that for large values of a the material would be insulating, while the example of monovalent metals like sodium showed that for small values it would be metallic. 

The question was, at what value of a would a metal-insulator transition occur The assumption (Mott 1949) was made that this would occur when the screened potential round each positive charge,... 

With neglect of multiple scattering, Mott (1972a) supposed that if EF—EC changed sign, causing a metal-insulator transition, or if a transition at mid-band resulted from a change of V then the metallic conductivity would drop to a minimum value... 

The susceptibility is expected to appear as in Fig. 4.9. In the first edition of this book we quoted results due to Quirt and Marko (1973) on metallic Si P near the concentration for the metal-insulator transition that show just this behaviour. However, it is now clear (see Chapter 5) that the transition in Si P is not of Mott type, so this must be accidental. 

Our understanding of conduction in liquid metals is based on the theory put forward by Ziman (1961).This is a weak-scattering theory that has proved highly satisfactory for the description of normal metals for which l a, and proves surprisingly satisfactory in many cases even when this is not the case (see Faber 1972, Mott and Davis 1979, Chap. 5). Most metal-insulator transitions in liquids occur in. the regime where l a. They can be induced in several ways. 

Mott, N. F Metal-Insulator Transitions, p 222. Taylor and Francis/Barnes and Noble, 1974. 

---